c.1300, "wanting in courage," now mostly in faint-hearted (mid-15c.), from O.Fr. faint "soft, weak, sluggish," pp. of faindre "avoid one's duty by pretending" (see feign). Sense of "weak, feeble" is early 14c. Meaning "producing a feeble impression upon the senses" is from
1650s. The verb originally meant "to lose heart" (mid-14c.); sense of "swoon" is c.1400. Related: Fainted; fainting.