'aposematic' originates from Greek elements (via New Latin/modern scientific coinage): the prefix 'apo-' (Greek ἀπό) meaning 'away from, off' and 'sēma' (Greek σῆμα) meaning 'sign' or 'mark'.

'aposematic' developed in zoological and entomological contexts in the late 19th to early 20th century from the noun 'aposematism' (the phenomenon of warning signals), which itself was formed from Greek roots; it entered modern English scientific usage as 'aposematic' to describe organisms with warning signals.

Initially formed to describe 'having a sign' (from Greek roots), it came to be used specifically for biological 'warning signals'—especially conspicuous coloration indicating toxicity or unpalatability.