Yours, Etc.: Origins and Uses of 8 Sign-Offs
early 13c., from Old French counseil (10c.) "advice, counsel; deliberation, thought," from Latin consilium "plan, opinion" (see consultation). As a synonym for "lawyer," first attested late 14c.
late 13c., from Old French conseiller "to advise, counsel," from Latin consiliari, from consilium "plan, opinion" (see counsel (n.)). Related: Counseled. Counseling "giving professional advice on social or psychological problems" dates from 1940.