c.1400, "to charge, allege," from O.Fr. surmis, pp. of surmettre "to accuse," from sur- "upon" + mettre "put," from L. mittere "to send" (see mission). Meaning "to infer conjecturally" is recorded from 1700. The noun meaning "inference, guess" is first found in Eng. 1590; earlier it was a legal term meaning "formal allegation" (1451).