marked by deep ill will; deliberately harmful; "a malevolent lie"; "poisonous hate...in his eyes"- Ernest Hemingway; "venomous criticism"; "vicious gossip"
A poisonous living thing can harm if it is eaten because it produces toxic substances. Not all poisonous organisms are venomous. For example, you are unlikely to die if a pufferfish bites you, but you may if you eat it.
an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).