Spanish irregular verbs#Vowel raising

Due to the rules of Spanish orthography, some predictable changes are needed to keep the same consonant sound before a or o and e or i, but these are not usually considered irregularities. The following examples use the first person plural of the present subjunctive:

• {{IPA|/k/}}: c—qu: {{Wikt-lang|es|tocar}} > {{Wikt-lang|es|toquemos}} (-car), {{Wikt-lang|es|delinquir}} > {{Wikt-lang|es|delincamos}} (-quir).
• {{IPA|/θ/}}: z—c: {{Wikt-lang|es|gozar}} > {{Wikt-lang|es|gocemos}} (-zar), {{Wikt-lang|es|vencer}} > {{Wikt-lang|es|venzamos}} (-cer).
• {{IPA|/x/}}: g—j: {{Wikt-lang|es|proteger}} > {{Wikt-lang|es|protejamos}} (-ger). But in verbs ending in -jar, the j is kept before e: {{Wikt-lang|es|mojar}} > {{Wikt-lang|es|mojemos}} (not {{lang|es|*mogemos}}).
• {{IPA|/ɡ/}}: g—gu: {{Wikt-lang|es|negar}} > {{Wikt-lang|es|neguemos}} (-gar), {{Wikt-lang|es|distinguir}} > {{Wikt-lang|es|distingamos}} (-guir).
• {{IPA|/ɡw/}}: gu—gü: {{Wikt-lang|es|averiguar}} > {{Wikt-lang|es|averigüemos}} (-guar).

Other predictable changes involve stress marks, i—y alternations and i-dropping, some of which are sometimes considered as irregularities. These examples are several forms of otherwise regular preterites:

• Stress mark on stressed i after a, e or o: {{Wikt-lang|es|caer}} > {{Wikt-lang|es|caímos}} (-caer), {{Wikt-lang|es|leer}} > {{Wikt-lang|es|leímos}} (-eer), {{Wikt-lang|es|oír}} > {{Wikt-lang|es|oímos}} (-ír, -oír); this does not apply to any G-verbs such as {{Wikt-lang|es|traer}} and its related forms.
• Stress mark not used in monosyllabic forms: {{Wikt-lang|es|liar}} > {{Wikt-lang|es|lie}} {{IPA|/lje/}}, {{Wikt-lang|es|lio}} {{IPA|/ljo/}}; {{Wikt-lang|es|ver}} > {{Wikt-lang|es|vi}}, {{Wikt-lang|es|vio}}. However, before 2010, the forms {{Wikt-lang|es|lié}} {{IPA|/liˈe/}} and {{Wikt-lang|es|lió}} {{IPA|/liˈo/}}, {{Wikt-lang|es|fié}} and {{Wikt-lang|es|fió}}, {{Wikt-lang|es|guié}} and {{Wikt-lang|es|guió}}, and {{Wikt-lang|es|crié}} and {{Wikt-lang|es|crió}} could also be written with the accent mark by writers who pronounce these forms as bisyllabic.[http://lema.rae.es/dpd/?key=tilde Diccionario panhispánico de dudas], "tilde"². n.1.2. But this option was not available for {{Wikt-lang|es|vio}}.
• Unstressed i is written y between non-silent vowels: {{Wikt-lang|es|caer}} > {{Wikt-lang|es|cayó}}, {{Wikt-lang|es|cayeron}} (-aer, -caer); {{Wikt-lang|es|construir}} > {{Wikt-lang|es|construyó}}, {{Wikt-lang|es|construyeron}} (-uir). This does not apply to verbs ending in -quir (for example, {{Wikt-lang|es|delinquir}} > {{Wikt-lang|es|delinquió}}, {{Wikt-lang|es|delinquieron}}).
• Unstressed i is dropped between ll or ñ and a vowel: {{Wikt-lang|es|bullir}} > {{Wikt-lang|es|bulló}} (not *bullió) (-llir/-ñir), {{Wikt-lang|es|tañer}} > {{Wikt-lang|es|tañó}} (-ñer).

There are two kinds of changes that can affect stem vowels of some Spanish verbs: diphthongization and vowel raising. Both changes affect -e- or -o- in the last (or only) syllable of a verb stem. Diphthongization changes -e- to -ie-, and -o- to -ue-. Vowel raising changes the mid vowels -e- and -o- to the corresponding high vowels: -i- and -u- respectively. Some verbs, in their various forms, can exhibit both kinds of changes (e.g. {{Wikt-lang|es|sentir|sentir}}, {{Wikt-lang|es|siente|siente}}, {{Wikt-lang|es|sintió|sintió}} (e-ie-i); {{Wikt-lang|es|dormir|dormir}}, {{Wikt-lang|es|duerme|duerme}}, {{Wikt-lang|es|durmió|durmió}}) (o-ue-u).

Some verbs with -e- or -o- in their stem are inherently diphthongizing, whereas others are not: their identities must be learned individually.

In a diphthongizing verb, the change turns -e- into -ie- and -o- into -ue- when the syllable in question is stressed, which in effect happens only in the singular persons and third-person plural of the present indicative and present subjunctive, and in the imperative (all other tenses and forms are stressed on their endings, not their stems). The dictionary form always has the vowel, not the diphthong, because, in the infinitive form, the stress is on the ending, not the stem. Exceptionally, the -u- of {{Wikt-lang|es|jugar|jugar}} (u-ue -gar, -jugar) and the -i- of {{Wikt-lang|es|adquirir|adquirir}} and {{Wikt-lang|es|inquirir|inquirir}} (i-ie) also are subject to diphthongization ({{Wikt-lang|es|juega}}, etc.; {{Wikt-lang|es|adquiere}}, etc.).

In word-initial position, *ie- is written ye- ({{Wikt-lang|es|errar|errar}} > {{Wikt-lang|es|yerro|yerro}}) (e-ie > ye) and *ue- is written hue- ({{Wikt-lang|es|oler|oler}} > {{Wikt-lang|es|huele|huele}}) (o-ue > hue, oler). Also, the -ue- diphthong is written -üe- after g, with the diaeresis to indicate that the letter is not silent ({{Wikt-lang|es|avergonzar|avergonzarse}} > {{Wikt-lang|es|avergüenzo|me avergüenzo}}) (reflexive, go-güe -zar).

The following examples show that all three conjugations (-ar, -er, and -ir verbs) include some diphthongizing verbs (only some tenses and persons are shown, for contrasting purposes):

(*) In Central America pensés, contés, etc. are used,Diccionario panhispánico de dudas, voseo, [http://lema.rae.es/dpd/srv/search?id=iOTUSehtID6mVONyGX#2121b section 2.1.2.1.b] but Spanish Royal Academy prescribes [http://lema.rae.es/drae/srv/search?id=UG2m51FHFVcRjK5gsirJ pienses], [http://lema.rae.es/drae/srv/search?id=CIhkF245jVcRjJO0DYu3 cuentes], etc., according to Rioplatense Spanish.

:(*) Only used in Spain. Formal conjugations of the plural imperative end in -d, but in colloquial use the most common conjugation ends in -r instead: pensar, contar, etc.

The verbs {{lang|es|sentir}} and {{lang|es|dormir}} also undergo vowel raising. Additional diphthongizing verbs include {{Wikt-lang|es|acordar|acordar(se)}} (o-ue), {{Wikt-lang|es|divertir|divertir(se)}} (e-ie), {{Wikt-lang|es|doler}} (o-ue), {{Wikt-lang|es|empezar}} (-zar e-ie, -ezar), {{Wikt-lang|es|encontrar}} (o-ue), {{Wikt-lang|es|entender}} (e-ie), {{Wikt-lang|es|llover}} (o-ue), {{Wikt-lang|es|morir}} (o-ue, -morir), {{Wikt-lang|es|mostrar}} (o-ue), {{Wikt-lang|es|mover}} (o-ue), {{Wikt-lang|es|poder}} (o-ue, -poder), {{Wikt-lang|es|probar}} (o-ue), {{Wikt-lang|es|querer}} (e-ie, -querer), {{Wikt-lang|es|recordar}} (o-ue), {{Wikt-lang|es|sentar|sentar(se)}} (e-ie-i), {{Wikt-lang|es|tener}} (e-ie, -tener, G-Verb), {{Wikt-lang|es|venir}} (e-ie, -venir, G-Verb), {{Wikt-lang|es|volar}} (o-ue), and {{Wikt-lang|es|volver}} (o-ue, -olver).

Many verbs with -e- or -o- in the root do not alternate. Common non-diphthongizing verbs include {{Wikt-lang|es|acercar|acercar(se)}}, {{Wikt-lang|es|beber}}, {{Wikt-lang|es|comer}}, {{Wikt-lang|es|comprar}}, {{Wikt-lang|es|conocer}}, {{Wikt-lang|es|correr}}, {{Wikt-lang|es|creer}}, {{Wikt-lang|es|deber}}, {{Wikt-lang|es|dejar}}, {{Wikt-lang|es|entrar}}, {{Wikt-lang|es|esperar}}, {{Wikt-lang|es|lamentar}}, {{Wikt-lang|es|llegar}}, {{Wikt-lang|es|llevar}}, {{Wikt-lang|es|meter}}, {{Wikt-lang|es|parecer}}, {{Wikt-lang|es|poner}}, {{Wikt-lang|es|prometer}}, {{Wikt-lang|es|quedar}}, {{Wikt-lang|es|regresar}}, {{Wikt-lang|es|responder}}, {{Wikt-lang|es|suceder}}, {{Wikt-lang|es|temer}}, and {{Wikt-lang|es|tomar}}.

Less frequent verbs of this kind are often a source of mistakes for children learning to speak, and also for some adults:

• {{Wikt-lang|es|rebosar|rebosar}} → {{lang|es|yo *rebueso}}, {{lang|es|él *rebuesa...}} instead of {{lang|es|yo reboso}}, {{lang|es|él rebosa...}}

Vowel raising appears only in verbs of the third conjugation (-ir verbs), and in this group it affects {{Wikt-lang|es|dormir|dormir}}, {{Wikt-lang|es|morir|morir}}, {{Wikt-lang|es|podrir|podrir}} (alternative of the more common {{Wikt-lang|es|pudrir|pudrir}}) and nearly all verbs which have -e- as their last stem vowel (e.g. {{Wikt-lang|es|sentir|sentir}}, {{Wikt-lang|es|repetir|repetir}}); exceptions include {{Wikt-lang|es|cernir}}, {{Wikt-lang|es|discernir}} and {{Wikt-lang|es|concernir}} (all three diphthongizing, e-ie).

The forms that exhibit the change can be described negatively as those in which the stem vowel is not diphthongized and the ending does not contain stressed iTerrell, Tracy D., and Salgués de Cargill, Maruxa, Lingüística aplicada a la enseñanza del español a anglohablantes (New York: Wiley, 1979), p. 97. or the -ir- sequence. In other words, vowel raising affects the forms whose endings do not contain an i which is not part of a diphthong, taking into account that diphthongizing overrides vowel raising.

In effect, for diphthongizing verbs (e.g. {{Wikt-lang|es|sentir}}, {{Wikt-lang|es|dormir}}), the vowel-raising forms are:

• the first-person and second-person plural of the present subjunctive (sintamos, sintáis, durmamos, durmáis);
• the gerund (sintiendo, durmiendo);
• the third-person singular and plural of the preterite (sintió, sintieron, durmió, durmieron);
• all forms of the imperfect subjunctive (sintiera/sintiese..., durmiera/durmiese...) and of the future subjunctive (sintiere..., durmiere...).

For non-diphthongizing verbs (e.g. {{Wikt-lang|es|pedir}}) it affects these same forms (pidamos, pidáis, pidiendo, pidió, pidieron, pidiera...), plus:

• in the present indicative, all singular forms and the third-person plural (pido, pides, pide, piden);
• the remaining forms of the present subjunctive (pida, pidas, pidan);
• the tú form of the imperative (pide).

The forms which do not undergo either diphthongizing or vowel raising are:

• the first-person and second-person plural of the present indicative (sentimos, sentís), because these forms have stressed i in their endings.
• the infinitive (sentir), past participle (sentido), imperfect indicative (sentía...) and the vos and vosotros/as forms of the imperative (sentí, sentid), for the same reason.
• the future (sentiré...) and conditional (sentiría...), whose endings contain the -ir- sequence.

Verbs which are diphthongizing and vowel-raising include:

• those ending in {{lang|es|-entir}} ({{Wikt-lang|es|sentir}}, {{Wikt-lang|es|mentir}}, {{Wikt-lang|es|arrepentirse}}...) and -ertir ({{Wikt-lang|es|convertir}}, {{Wikt-lang|es|advertir}}...).
• those ending in {{lang|es|-erir}} ({{Wikt-lang|es|herir}}, {{Wikt-lang|es|requerir}}, {{Wikt-lang|es|preferir}}, {{Wikt-lang|es|digerir}}...), except {{Wikt-lang|es|aterir}}.
• {{Wikt-lang|es|venir}} and derived verbs ({{Wikt-lang|es|convenir}}, {{Wikt-lang|es|prevenir}}...), in the forms that do not undergo other overriding irregularities.
• {{Wikt-lang|es|dormir}} and {{Wikt-lang|es|morir}}.

The diphthongizing -er verb {{Wikt-lang|es|poder}} exceptionally undergoes vowel raising in the gerund ({{Wikt-lang|es|pudiendo|pudiendo}}), but the first- and second-person plural of the present subjunctive are regular (podamos, podáis).

Non-diphthongizing vowel-raising verbs include:

• those ending in -edir ({{Wikt-lang|es|medir}}, {{Wikt-lang|es|pedir}}, {{Wikt-lang|es|despedir}}...), -etir ({{Wikt-lang|es|competir}}, {{Wikt-lang|es|repetir}}) and -egir ({{Wikt-lang|es|corregir}}, {{Wikt-lang|es|elegir}}...; note forms with j before a/o such as corrijo, corrija).
• those ending in -eír ({{Wikt-lang|es|reír}}, {{Wikt-lang|es|sonreír}}, {{Wikt-lang|es|freír}}, {{Wikt-lang|es|desleír}}). Double i that would result is simplified ({{lang|es|rieron}}, not {{lang|es|*riieron}} or {{lang|es|*riyeron}}). The stressed i in contact with a/e/o must take an acute accent (río, ríe, ría) but monosyllabic forms of the preterite do not have it (rio, riais, but rió and riáis were valid before 2010 if pronounced in two syllables).
• those ending in -eñir ({{Wikt-lang|es|teñir}}, {{Wikt-lang|es|ceñir}}...). The unstressed i between ñ and a vowel is dropped (tiñendo, tiñó, tiñeron, tiñera...).
• {{Wikt-lang|es|decir}} and derived verbs ({{Wikt-lang|es|bendecir}}, {{Wikt-lang|es|predecir}}...), in the forms that do not undergo other overriding irregularities.
• {{Wikt-lang|es|vestir}} and derived verbs.
• {{Wikt-lang|es|embestir}}.
• {{Wikt-lang|es|podrir}}. The affected forms are equal to those derived from the more usual infinitive {{Wikt-lang|es|pudrir}}, which is regular except in the past participle {{Wikt-lang|es|podrido}}.

The vowel-raising verb {{Wikt-lang|es|erguir}} is usually diphthongizing (with ye- forms such as yergo...). Non-diphthongizing forms are valid but rare (irgo...).

Diphthongs in the infinitive may be preserved throughout the conjugation or broken in the forms which are stressed on the stem, depending on whether the i or u in contact with a/e/o take the stress or not. The stressed vowel is marked bold in the examples: {{Wikt-lang|es|cambiar}} > cambio, but {{Wikt-lang|es|enviar}} > envío (requiring an acute accent to indicate the resulting hiatus). The Real Academia Española does not consider either behaviour as irregular, but illustrates each with six "regular" models, one for each possible diphthong in the infinitive: {{Wikt-lang|es|anunciar}}, {{Wikt-lang|es|averiguar}}, {{Wikt-lang|es|bailar}}, {{Wikt-lang|es|causar}}, {{Wikt-lang|es|peinar}} and {{Wikt-lang|es|adeudar}} for diphthong-keeping verbs and {{Wikt-lang|es|enviar}}, {{Wikt-lang|es|actuar}}, {{Wikt-lang|es|aislar}}, {{Wikt-lang|es|aunar}}, {{Wikt-lang|es|descafeinar}} and {{Wikt-lang|es|rehusar}} for diphthong-breaking ones. Remember that the presence of a silent h does not break a diphthong, so a written accent is needed anyway in rehúso.

All verbs ending in -guar are diphthong-keeping, as well as {{Wikt-lang|es|saciar}}, {{Wikt-lang|es|desairar}}, {{Wikt-lang|es|restaurar}} and {{Wikt-lang|es|reinar}}. Two diphthongs are kept in {{Wikt-lang|es|desahuciar}} > desahucio (again the -h- makes no difference), which thus follows both the anunciar and causar models.

Diphthong-breaking verbs include {{Wikt-lang|es|ahincar}}, {{Wikt-lang|es|aislar}}, {{Wikt-lang|es|aunar}}, {{Wikt-lang|es|aullar}}, {{Wikt-lang|es|maullar}}, {{Wikt-lang|es|aupar}}, {{Wikt-lang|es|aliar}}, {{Wikt-lang|es|vaciar}}, {{Wikt-lang|es|contrariar}}, {{Wikt-lang|es|evaluar}}, {{Wikt-lang|es|habituar}}, {{Wikt-lang|es|reunir}}. The verbs {{Wikt-lang|es|criar}}, {{Wikt-lang|es|fiar}}, {{Wikt-lang|es|guiar}}, {{Wikt-lang|es|liar}} and {{Wikt-lang|es|piar}} are also diphthong-breaking (crío, guíe), but when the stress falls on the endings the resulting forms are generally considered as monosyllables and thus written without accent: crie, fie, guiais, lieis.... In spite of that, the regular accentuation rules can also be used if they are pronounced as bisyllabic: crié, guiáis....

For the verbs {{Wikt-lang|es|licuar}} and {{Wikt-lang|es|adecuar}} both options are valid: adecuo or adecúo.

The ui diphthong in {{Wikt-lang|es|cuidar}} is kept throughout the conjugation despite the fact of the i getting the stress in forms such as cuido (written without stress mark).

All verbs ending in -uir (e.g. {{Wikt-lang|es|construir}}, {{Wikt-lang|es|disminuir}}, {{Wikt-lang|es|distribuir}}) add a medial -y- before all endings not starting with i: construyo, construyes, construya... Taking into account that these verbs also undergo the change of unstressed intervocalic i to y (see orthographic changes above), they have many forms containing y.

This also applies to the forms of {{Wikt-lang|es|oír}} and {{Wikt-lang|es|desoír}} that do not undergo the -ig- change: oyes, oye, oyen…

Some regular forms of {{Wikt-lang|es|fluir}}, {{Wikt-lang|es|fruir}} and {{Wikt-lang|es|huir}} are written without stress mark if considered monosyllabic, but may bear it if pronounced as bisyllabic: vosotros huis or huís (present), yo hui or huí (preterite).

The verb {{Wikt-lang|es|argüir}} loses the diaeresis before y: arguyo, arguyó… (gü-gu, -güir).

In er and ir verbs, the first person singular of the present indicative and the whole present subjunctive are the only forms whose endings start with o/a instead of e/i. These two different phonetic environments made Latin forms evolve differently in many verbs, leading to irregularities.

Whenever the first person singular of the present indicative has an irregularity other than diphthongizing, but still ends in -o, the whole present subjunctive shares the same irregularity. For example:

• {{Wikt-lang|es|hacer}}: hago, haga... (-hacer, G-Verb)

• {{Wikt-lang|es|lucir}}: luzco, luzca... (c-zc, -cir)
• {{Wikt-lang|es|caber}}: quepo, quepa... (-caber)

• {{Wikt-lang|es|ver}}: veo, vea...; {{Wikt-lang|es|prever}}: preveo, prevea... (-ver)

When the first person singular of the present indicative does not end in -o, the present subjunctive is also irregular, but in a different way:

• {{Wikt-lang|es|ser}}: soy, sea... (-ser, Oy-Verb)
• {{Wikt-lang|es|ir}}: voy, vaya... (-ir, Oy-Verb)
• {{Wikt-lang|es|haber}}: he, haya (-haber)
• {{Wikt-lang|es|saber}}: sé, sepa... (-saber)

Before o (in the first person singular of the indicative present tense) and a (that is, in all persons of the present subjunctive), the so-called G-verbs (sometimes "Go-Yo verbs", "Yo-Go" verbs, or simply "Go" verbs) add a medial -g- after l and n (also after s in asir), add -ig- when the root ends in a vowel, or substitute -c- for -g-. This change overrides diphthongization (tener, venir) but combines with vowel-raising (decir). Many of these verbs are also irregular in other ways. For example:

• {{Wikt-lang|es|salir}}: yo salgo, tú sales... Stem: sal- (-salir)
• {{Wikt-lang|es|valer}}: yo valgo, tú vales... Stem: val- (-valer)
• {{Wikt-lang|es|poner}}: yo pongo, tú pones... Stem: pon- (-poner)
• {{Wikt-lang|es|tener}}: yo tengo, tú tienes... Stem: ten-, tien- (e-ie) (-tener)
• {{Wikt-lang|es|venir}}: yo vengo, tú vienes... Stem: ven-, vien- (e-ie) (-venir)
• {{Wikt-lang|es|caer}}: yo caigo, tú caes... Stem: ca-
• {{Wikt-lang|es|traer}}: yo traigo, tú traes... Stem: tra-
• {{Wikt-lang|es|oír}}: yo oigo, tú oyes... Stem: o-, oy-
• {{Wikt-lang|es|hacer}}: yo hago, tú haces... Stem: hac-, haz- (-hacer)
• {{Wikt-lang|es|satisfacer}}: yo satisfago, tú satisfaces… Stem: satisfac-, satisfaz-
• {{Wikt-lang|es|decir}}: yo digo, tú dices... Stem: dec-, dic- (e-i) (-decir)
• {{Wikt-lang|es|asir}}: yo asgo, tú ases... Stem: as-

This group of verbs—which originated in the Latin inchoative verbs but now includes other verbs as well—substitute -zc- for stem-final -c- before o and a. The group includes nearly all verbs ending in -acer (except {{Wikt-lang|es|hacer}} and derived verbs), -ecer (except {{Wikt-lang|es|mecer}} and {{Wikt-lang|es|remecer}}), -ocer (except {{Wikt-lang|es|cocer}} and derived verbs), and -ucir. For example:

• {{Wikt-lang|es|nacer}}: yo nazco, tú naces...
• {{Wikt-lang|es|crecer}}: yo crezco, tú creces...
• {{Wikt-lang|es|conocer}}: yo conozco, tú conoces...
• {{Wikt-lang|es|producir}}: yo produzco, tú produces... (-ducir)
• {{Wikt-lang|es|yacer}}: yo yazco/yazgo/yago, tú yaces... (-yacer)

{{Wikt-lang|es|Yacer}} may alternatively be conjugated with -zc- ({{Wikt-lang|es|yazco}}), -g- (G-Verb) ({{Wikt-lang|es|yago}}), or a compromise -zg- ({{Wikt-lang|es|yazgo}}).

Some -er and -ir verbs (most G-verbs plus {{Wikt-lang|es|haber}}, {{Wikt-lang|es|saber}}, {{Wikt-lang|es|poder}} and {{Wikt-lang|es|querer}}) also change their stem in the future and conditional tenses. This involves syncope:

• Just dropping the infinitive e: {{Wikt-lang|es|haber}} → habré..., {{Wikt-lang|es|saber}} → sabré..., {{Wikt-lang|es|poder}} → podré..., {{Wikt-lang|es|querer}} → {{lang|es|querré}}...
• Dropping the infinitive e/i and padding the resulting *-lr-/*-nr- with an epenthetic -d-: {{Wikt-lang|es|tener}} → tendré..., {{Wikt-lang|es|poner}} → {{lang|es|pondré}}..., {{Wikt-lang|es|venir}} → {{lang|es|vendré}}..., {{Wikt-lang|es|valer}} → {{lang|es|valdré}}..., {{Wikt-lang|es|salir}} → {{lang|es|saldré}}...
• Dropping the infinitive -ce- or -ec-: {{Wikt-lang|es|hacer}} → haré..., {{Wikt-lang|es|deshacer}} → desharé..., {{Wikt-lang|es|decir}} → diré...
• {{Wikt-lang|es|predecir}}, {{Wikt-lang|es|contradecir}} and {{Wikt-lang|es|desdecir}} may share this irregularity (prediré...) or, more commonly, use the regular forms (predeciré). For {{Wikt-lang|es|bendecir}} and {{Wikt-lang|es|maldecir}} only the regular forms are used (bendeciré...).

Many of these verbs also have shortened tú imperative forms (apocope): tener → {{Wikt-lang|es|ten}}, contener → {{Wikt-lang|es|contén}}, poner → {{Wikt-lang|es|pon}}, disponer → {{Wikt-lang|es|dispón}}, venir → {{Wikt-lang|es|ven}}, salir → {{Wikt-lang|es|sal}}, hacer → {{Wikt-lang|es|haz}}, decir → {{Wikt-lang|es|di}}. However, all verbs derived from decir are regular in this form: bendice, maldice, desdícete, predice, contradice.

Some verbs (including most G-verbs and most verbs ending in {{lang|es|-ducir}}) have a somewhat different stem in the preterite. These stems are very old and often are found in Latin as well. The same irregular stem is also found in the imperfect subjunctive (both in -ra and -se forms) and the future subjunctive. These stems are anomalous also because:

• they are stressed in the first and third persons singular, ending in unstressed -e and -o respectively (while in all other cases the preterite is stressed on the suffix).
• the rest of the endings are the usual for -er/-ir verbs, even for the -ar verbs {{Wikt-lang|es|estar}} and {{Wikt-lang|es|andar}}.
• in the verbs with -je preterite ({{Wikt-lang|es|decir}}, {{Wikt-lang|es|traer}}, and most verbs ending in {{lang|es|-ducir}}) unstressed i is dropped between the j and a vowel: {{lang|es|ellos trajeron}}, {{lang|es|yo trajera}}... This does not happen with regular or vowel-raising -ger/-jer/-gir/-jir verbs ({{Wikt-lang|es|proteger}} > {{lang|es|protegieron}}, {{Wikt-lang|es|tejer}} > {{lang|es|tejieron}}, {{Wikt-lang|es|corregir}} > {{lang|es|corrigieron}}, {{Wikt-lang|es|crujir}} > {{lang|es|crujieron}}).

{{further|Comparison of Portuguese and Spanish#Irregular verbs}}

Examples:

• {{Wikt-lang|es|estar}}: yo estuve, tú/vos estuviste(s), él estuvo..., ellos estuvieron; yo estuviera...
• {{Wikt-lang|es|andar}}: yo anduve, tú/vos anduviste(s), él anduvo..., ellos anduvieron; yo anduviera...
• {{Wikt-lang|es|tener}}: yo tuve, tú/vos tuviste(s), él tuvo..., ellos tuvieron; yo tuviera...
• {{Wikt-lang|es|haber}}: yo hube, tú/vos hubiste(s), él hubo..., ellos hubieron; yo hubiera...
• {{Wikt-lang|es|caber}}: yo cupe, tú/vos cupiste(s), él cupo..., ellos cupieron; yo cupiera...
• {{Wikt-lang|es|saber}}: yo supe, tú/vos supiste(s), él supo..., ellos supieron; yo supiera...
• {{Wikt-lang|es|venir}}: yo vine, tú/vos viniste(s), él vino..., ellos vinieron; yo viniera...
• {{Wikt-lang|es|querer}}: yo quise, tú/vos quisiste(s), él quiso…, ellos quisieron; yo quisiera…
• {{Wikt-lang|es|poder}}: yo pude, tú/vos pudiste(s), él pudo..., ellos pudieron; yo pudiera...
• {{Wikt-lang|es|poner}}: yo puse, tú/vos pusiste(s), él puso..., ellos pusieron; yo pusiera...
• {{Wikt-lang|es|hacer}}: yo hice, tú/vos hiciste(s), él hizo..., ellos hicieron; yo hiciera...
• {{Wikt-lang|es|satisfacer}}: yo satisfice, tú/vos satisficiste(s), él satisfizo…, ellos satisficieron; yo satisficiera…
• {{Wikt-lang|es|traer}}: yo traje, tú/vos trajiste(s), él trajo…, ellos trajeron; yo trajera…
• {{Wikt-lang|es|reducir}}: yo reduje, tú/vos redujiste(s), él redujo..., ellos redujeron; yo redujera...
• {{Wikt-lang|es|decir}}: yo dije, tú/vos dijiste(s), él dijo..., ellos dijeron; yo dijera...

The verb {{Wikt-lang|es|ver}} in modern Spanish has a regular -er verb preterite (yo vi, tú viste, él vio – note the lack of written accent on monosyllables), but in archaic texts the irregular preterite forms yo vide, él vido, etc. are sometimes seen.

{{main|List of Spanish irregular participles}}

A number of verbs have irregular past participles, sometimes called "strong" because the change is in the root, rather than an ending. This includes verbs which are irregular in many other ways, such as {{Wikt-lang|es|poner}} and {{Wikt-lang|es|decir}}, but for some other verbs this is their only irregularity (such as {{Wikt-lang|es|abrir}} and {{Wikt-lang|es|romper}}), while some very irregular verbs (such as {{Wikt-lang|es|ser}} and {{Wikt-lang|es|ir}}) have regular past participles. Examples:

• {{Wikt-lang|es|abrir}} → {{Wikt-lang|es|abierto}}, {{Wikt-lang|es|cubrir}} → {{Wikt-lang|es|cubierto}}
• {{Wikt-lang|es|morir}} → {{Wikt-lang|es|muerto}}, {{Wikt-lang|es|volver}} → {{Wikt-lang|es|vuelto}}, {{Wikt-lang|es|solver}} → {{Wikt-lang|es|suelto}}
• {{Wikt-lang|es|romper}} → {{Wikt-lang|es|roto}}, {{Wikt-lang|es|escribir}} → {{Wikt-lang|es|escrito}}
• {{Wikt-lang|es|ver}} → {{Wikt-lang|es|visto}}, {{Wikt-lang|es|poner}} → {{Wikt-lang|es|puesto}}
• {{Wikt-lang|es|decir}} → {{Wikt-lang|es|dicho}}, {{Wikt-lang|es|hacer}} → {{Wikt-lang|es|hecho}}, {{Wikt-lang|es|satisfacer}} → {{Wikt-lang|es|satisfecho}}

Most of these verbs have derivatives with the same irregularity. For example, alongside volver → vuelto and poner → puesto, there are {{Wikt-lang|es|devolver}} → {{Wikt-lang|es|devuelto}} and {{Wikt-lang|es|componer}} → {{Wikt-lang|es|compuesto}}; alongside {{Wikt-lang|es|decir}} → {{Wikt-lang|es|dicho}} there is {{Wikt-lang|es|predecir}} → {{Wikt-lang|es|predicho}} (but note {{Wikt-lang|es|bendecir}} → {{Wikt-lang|es|bendecido}}, {{Wikt-lang|es|maldecir}} → {{Wikt-lang|es|maldecido}} are regular, though they also have the adjectival forms {{Wikt-lang|es|bendito}} and {{Wikt-lang|es|maldito}}). Similarly {{Wikt-lang|es|previsto}}, {{Wikt-lang|es|rehecho}}, {{Wikt-lang|es|descubierto}}, {{Wikt-lang|es|supuesto}}, etc. Solver is obsolete, but its derivatives {{Wikt-lang|es|absolver}} and {{Wikt-lang|es|resolver}} ({{Wikt-lang|es|absuelto}}, {{Wikt-lang|es|resuelto}}) are in common use. The participle of {{Wikt-lang|es|describir}} is {{Wikt-lang|es|descrito}} in some regions, but {{Wikt-lang|es|descripto}} in others.

There are three verbs that have both a regular and an irregular past participle. Both forms may be used when conjugating the compound tenses and the passive voice with the auxiliary verbs {{Wikt-lang|es|haber}} and {{Wikt-lang|es|ser}}, but the irregular form is generally the only one used as an adjective:

• {{Wikt-lang|es|freír}} → {{Wikt-lang|es|freído|he freído}} or {{Wikt-lang|es|frito|he frito}}, but papas fritas.
• {{Wikt-lang|es|imprimir}} → {{Wikt-lang|es|imprimido|he imprimido}} or {{Wikt-lang|es|impreso|he impreso}}, but papeles impresos.
• {{Wikt-lang|es|proveer}} → {{Wikt-lang|es|proveído|he proveído}} or {{Wikt-lang|es|provisto|he provisto}}, but una despensa bien provista is far more usual than una despensa bien proveída.

A number of other "strong" past participles, such as {{Wikt-lang|es|pinto}}, {{Wikt-lang|es|ducho}}, {{Wikt-lang|es|electo}}, and a number of others, are obsolete for general use, but are occasionally used in Spain (and to a much lesser extent in Spanish America) among educated, style-conscious writers, or in linguistic archaisms such as proverbs (refranes).

{{anchor|ser}}

The verbs {{Wikt-lang|es|ser}} (to be) and {{Wikt-lang|es|ir}} (to go) both exhibit irregularities in the present, imperfect and preterite forms (note that these two verbs have the same preterite fui). Together with {{Wikt-lang|es|ver}} (to see) and {{Wikt-lang|es|prever}} (to foresee), they are the only four verbs with irregular imperfect indicative. Their tú imperative forms are sé, ve (for both ir and ver, although {{Wikt-lang|es|mirar}} is more common than ver in commands), and prevé. Their vos imperative forms are sé, andá (the verb {{Wikt-lang|es|andar}} replaces ir), ve and prevé.

Note that whenever the preterite is irregular, the imperfect subjunctive (-ra and -se forms) and the dated future subjunctive (-re) share the same irregularity; indeed, these tenses may always be correctly formed by substituting the appropriate endings for the -ron ending of the third person plural preterite: fueron > fuera/fuese...; fuere....

{{anchor|estar}}

The verbs {{Wikt-lang|es|dar}} (to give) and {{Wikt-lang|es|estar}} (to be) both exhibit irregularities in the present indicative and present subjunctive because their stems cannot be stressed (in dar the stem is just d-, in estar it was originally st-). The form dé is so written to distinguish it from the preposition {{Wikt-lang|es|de}}. Both verbs are also irregular in the preterite and derived tenses: dar follows the pattern of regular -er/-ir verbs, while estar has an anomalous preterite stem and follows the corresponding common pattern:

{{wiktionary category|type=Spanish irregular verbs|category=Spanish irregular verbs}}

• [http://lema.rae.es/drae/ Dictionary of the Royal Spanish Academy]. It features a Conjugar button in each verb entry.
• [http://conjugador.onoma.es Onoma] Spanish conjugator. It provides information about the irregularities and conjugates invented verbs.
• [https://web.archive.org/web/20081206065816/http://www.onlinespanishhelp.com/vocabulary/Common%20Irregular%20Verbs Common irregular Spanish verbs and audio examples]
• [http://www.donquijote.org/spanishlanguage/verbs/ Spanish verb conjugator] don Quijote Spanish School
• [http://www.idiomax.com/online-verb-conjugation.aspx Online Spanish verb conjugation] Free online Spanish verb conjugation
• [http://www.conjugacion.es Spanish conjugation] Spanish conjugator. 12,000 verbs conjugated.
• [http://lema.rae.es/dpd/ Diccionario panhispánico de dudas]. [http://lema.rae.es/dpd/apendices/apendice1.html Apéndice 1: Modelos de conjugación verbal].
• [https://decimos.net decimos.net] A Spanish verb conjugator, partly based on this Wikipedia article, that explains each conjugated form step by step.
• [https://howismyspanish.com/all-irregular-spanish-verbs/ List of all Spanish irregular verbs] Complete list of over 270 Spanish irregular verbs.

{{Language verbs}}

Irregular verbs

Category:Indo-European verbs