an account of the history of a particular word or element of a word.
3.
the study of historical linguistic change, esp. as manifested in individual words.
Origin: 1350–1400; ME < L etymologia < Gk etymología, equiv. to etymológ(os) studying the true meanings and values of words (étymo(s) true (see etymon) + lógos word, reason) + -ia-y3