pisidiid
/pɪˈsɪdɪɪd/Zoology
noun
A member of the family Pisidiidae of small, rounded, freshwater bivalve molluscs having fused siphons; a pea mussel, a pea shell. rare.
adjective
Of 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 (C. Pfeiffer Naturgeschichte Deutsch. Land- u. Süsswasser-Mollusken I. 17; from classical Latin pisum pea + -idium) + -idae.