univalve

Meanings

1. 1
   adj

   having a shell formed from one piece or valve, especially as opposed to a bivalve shell

   The collection placed univalve shells in a separate cabinet from clams and oysters.

2. 2
   noun

   a univalve shell or, in older zoological classification, a mollusc such as a gastropod that bears one

   The naturalist identified the specimen as a marine univalve.

Formed from uni- ("one") + valve. Seventeenth-century zoology used univalve both for a one-piece shell and for the mollusc possessing it, contrasting it with bivalve shells made of two hinged parts.

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