Main Entry: the·rap·sid

Pronunciation: \thə-ˈrap-səd\

Function: noun

Etymology: New Latin Therapsida, from ther- mammal (from Greek thēr wild animal) + apsid-, apsis arch, vault — more at fierce, apsis

Date: 1912

: any of an order (Therapsida) of Permian and Triassic synapsid reptiles considered ancestors of the mammals

— therapsid adjective