Meaning

noun a perceptible indication of something not immediately apparent (as a visible clue that something has happened)

noun a public display of a message

noun any nonverbal action or gesture that encodes a message

originFrom Middle English signen, seinen, seinien, partly from Old English seġnian (“to mark; sign”) and partly from Anglo-Norman seigner, seiner et al., Old French signer et al., and their source Latin signāre (“to mark, seal, indicate, signify”); all from Latin signum (“a mark, sign”); see Etymology 1, above. Compare sain.

Etymology from Wiktionary, CC BY-SA 3.0