morphant
An organism which has been treated with a morpholino antisense oligo to temporarily knock down expression of a targeted gene is called a morphant.
Background
This term was coined by Prof. Steve Ekker{{cite journal |author=Ekker SC |title=Morphants: a new systematic vertebrate functional genomics approach |journal=Yeast |volume=17 |issue=4 |pages=302–306 |date=December 2000 |pmid=11119307 |pmc=2448384 |doi=10.1002/1097-0061(200012)17:4<302::AID-YEA53>3.0.CO;2-#}} to describe the zebrafish with which he was experimenting; by knocking down embryonic gene expression using Morpholinos, Prof. Ekker "phenocopied" known zebrafish mutations, that is, he raised embryos that had the same morphological phenotype as embryonic zebrafish with specific gene mutations. Prof. Ekker's papers{{cite journal |vauthors=Nasevicius A, Ekker SC |title=Effective targeted gene 'knockdown' in zebrafish |journal=Nat. Genet. |volume=26 |issue=2 |pages=216–20 |date=October 2000 |pmid=11017081 |doi=10.1038/79951 |s2cid=21451111 }} and presentations describing morphant phenocopies of mutant phenotypes, in combination with Prof. Janet Heasman's earlier work{{cite journal |vauthors=Heasman J, Kofron M, Wylie C |title=Beta-catenin signaling activity dissected in the early Xenopus embryo: a novel antisense approach |journal=Dev. Biol. |volume=222 |issue=1 |pages=124–34 |date=June 2000 |pmid=10885751 |doi=10.1006/dbio.2000.9720 |doi-access=free }} with Morpholinos in Xenopus embryos, led to rapid adoption of Morpholino technology by the developmental biology community.