late 14c., ethimolegia "facts of the origin and development of a word," from Old French et(h)imologie (14c., Modern French étymologie), from Latin etymologia, from Greek etymologia, properly "study of the true sense (of a word)," from etymon "true sense" (neuter of etymos "true, real, actual," related to eteos "true") + -logia "study of, a speaking of" (see -logy).
In classical times, of meanings; later, of histories. Latinized by Cicero as veriloquium. As a branch of linguistic science, from 1640s. Related: Etymological; etymologically.