faint (adj.)
c.1300, "wanting in courage," now mostly in faint-hearted (mid-15c.), from Old French feint "soft, weak, sluggish," past participle of feindre "hesitate, falter, be indolent, show weakness, 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.
faint (v.)
"grow weak" (c.1300); "lose heart" (mid-14c.); see faint (adj.). Sense of "swoon" is c.1400. Related: Fainted; fainting.