containing poison or producing poison:
Some mushrooms are extremely poisonous.
poisonous gases such as hydrogen sulfide
She was bitten on the ankle by a poisonous snake.
The berries are poisonous to birds.
full of bad and unfriendly feelings:
the poisonous atmosphere of the office
3 British English
someone who is poisonous seems to get pleasure from causing arguments, unhappiness etc:
That poisonous bastard Lucett told Morris I was seeing his wife.