Antidote (noun)

1. A medicine or other substance used to counteract the effects of a poison.
2. A remedy or cure for a specific problem or condition.

Origin:

From middle english antidot, from old french antidot, from latin antidotum, from greek ἀντίδοτον (antidoton, "given against"), from ἀντί (anti, "against") + δότος (dotos, "give.n")

Examples:

1. Atropine is an antidote for nerve gas.
2. The doctor gave him an antidote to counteract the effects of the poison.
3. The antidote for snake venom is antivenom.
4. Love is the antidote to hate.
5. Laughter is the best antidote for stress.