(1):

(n.) Whatever tends to prevent mischievous effects, or to counteract evil which something else might produce.

(2):

(v. t.) To counteract or prevent the effects of, by giving or taking an antidote.

(3):

(v. t.) To fortify or preserve by an antidote.

(4):

(n.) A remedy to counteract the effects of poison, or of anything noxious taken into the stomach; - used with against, for, or to; as, an antidote against, for, or to, poison.