antidote (n.) Look up antidote at Dictionary.com
"remedy counteracting poison," 1510s (earlier in English as a Latin word), from Middle French antidot and directly from Latin antidotum "a remedy against poison," from Greek antidoton "given as a remedy," literally "given against," verbal adjective of antididonai "give in return," from anti- "against" + didonai "to give" (see date (n.1)). Compare Middle English antidotarie "treatise on drugs or medicines" (c.1400).