baptisterium

{{Short description|Ancient Roman bathing basin}}

{{For|the building housing a baptismal font|Baptistery}}

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Image:Frigidarium of the Old Baths at Pompeii by Overbeck.png of the thermae at Pompeii]]

In classical antiquity, a baptisterium ({{langx|grc|βαπτιστήριον}}) was a large basin installed in private or public baths into which bathers could plunge, or even swim about.Epist. ii. 17, 11 (cited by Peck) It is more commonly called natatorium or piscina.