footwear, early 14c., from Old French bote "boot" (12c.), with corresponding words in Provençal and Spanish, of unknown origin, perhaps from a Germanic source. Originally for riding boots only. An old Dorsetshire word for "half-boots" was skilty-boots [Halliwell, Wright].
"profit, use," Old English bot "help, relief, advantage; atonement," literally "a making better," from Proto-Germanic *boto (see better (adj.)). Cf. German Buße "penance, atonement," Gothic botha "advantage." Now mostly in phrase to boot (Old English to bote).
"to kick," 1877, American English, from boot (n.1). Generalized sense of "eject, kick out" is from 1880. Related: Booted; booting.
"start up a computer," 1975, from bootstrap (v.), a 1958 derived verb from bootstrap (n.) in the computer sense.