The story
An appellativization from Equid(ae) minus -ae (a pattern that recurs with many -idae names), or, by surface analysis, Latin equ(us) (“horse”) + -id.
Etymology from Wiktionary, CC BY-SA 4.0.
equid
Today it means: Any animal of the taxonomic family Equidae, including any equine (horse, zebra, ass, mule, etc.). Full definition →