Antidote

An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον (pharmakon antidoton), "(medicine) given as a remedy". An older term in English which is now rare is atterlothe, derived from "atter". Antidotes for anticoagulants are sometimes referred to as reversal agents.