"to brown with heat," 1398, from O.Fr.
toster "to toast or grill" (12c.), from V.L.
*tostare (cf. It.
tostare, Sp.
tostar), frequentative of L.
torrere (pp.
tostus) "to parch" (see
terrain). The noun meaning "a toasted piece of bread" is attested from c.1430; slang meaning "a goner, person or thing already doomed or destroyed" is recorded by 1987, perhaps from notion of computer circuits being "fried," and with unconscious echoes of earlier fig. phrase
to be had on toast (1886) "to be served up for eating."
Toaster in the electrical appliance sense first recorded 1913.
Toasty "warm and comfortable" is recorded from 1890.