noun
rare ZoologyA member of the family Pisidiidae of small, rounded, freshwater bivalve molluscs having fused siphons; a pea mussel, a pea shell.
adjective
ZoologyOf or relating to the family Pisidiidae of freshwater bivalve molluscs.
Origin
Late 19th century; earliest use found in Isaac Funk (1839–1912), publisher and reformer. From scientific Latin Pisidiidae, family name, alteration of Pisidiadae (J. E. Gray 1857) from Pisidium, genus name + -idae.
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