early 13c., "gesture or motion of the hand," from Old French signe "sign, mark, signature," from Latin signum "mark, token, indication, symbol," from PIE root *sekw- "point out" (see see).
Meaning "a mark or device having some special importance" is recorded from late 13c.; that of "a miracle" is from c.1300. Sense of "characteristic device attached to the front of an inn, shop, etc., to distinguish it from others" is first recorded mid-15c. Ousted native token. In some uses, the word probably is a shortening of ensign. Sign language is recorded from 1847; earlier hand-language (1670s).
c.1300, "to make the sign of the cross," from Old French signer, from Latin signare, from signum (see sign (n.)). Sense of "to mark, stamp" is attested from mid-14c.; that of "to affix one's name" is from late 15c. Meaning "to communicate by sign language" is recorded from 1700. Related: Signed; signing.