Definition from Wiktionary, the free dictionary
univalve (not comparable)
- having one valve, typically used to refer to mollusks, notably slugs and snails.
- consisting of a single valve or piece, used to refer to a shell.
univalve (plural univalves)
- A univalve mollusk or its shell.
The term univalve is now considered outdated in scientific classification, and the term gastropod is preferred.