early 15c., "to bend inward," from Latin inflectere (past participle inflexus) "to bend in, bow, curve," figuratively, "to change, alter, influence," from in- "in" (see in- (1)) + flectere "to bend" (see flexible). Grammatical sense "to vary by change of form" (especially at the end of a word) is from 1660s. Related: Inflected; inflecting.
<a href="https://www.etymonline.com/word/inflected">Etymology of inflected by etymonline</a>
Harper, D. (n.d.). Etymology of inflected. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/inflected