"rich brown pigment," 1821, from Italian seppia "cuttlefish," from Latin sepia "cuttlefish," from Greek sēpia "cuttlefish," a word of uncertain origin. Some connect it to sēpein "to make rotten" (see sepsis). Beekes finds this "semantically possible" (perhaps referring to the ink that smells as if it is rotten) but formally problematic and suggests it might be Pre-Greek.
The color was that of brown paint or ink prepared from the fluid secretions of the cuttlefish. The meaning "a sepia drawing" is recorded from 1863. English sepia in the sense of "cuttlefish" is attested from late 14c. but is rare. The Latin word also is the source of Spanish xibia, French seiche, etc., with many dialectal variants. Related: Sepian; sepic.