antidote

Concise Oxford English Dictionary © 2008 Oxford University Press:
antidote/ˈantidəʊt/

▶noun

• 1 a medicine taken to counteract a particular poison.

• 2 something that counteracts an unpleasant feeling or situation: laughter is a good antidote to stress.

– derivatives
antidotal adjective.

– origin ME: via L., from Gk antidoton, from anti- ‘against’ + didonai ‘give’.