Use venomous when an animal or organism delivers a toxin through a bite, sting, or similar attack.

Use poisonous when something is dangerous because its toxins are absorbed, touched, or consumed.

So the difference is not just about danger. It is about how the toxin enters the body:

✅ Cobras are venomous.
A cobra delivers venom through its bite.

✅ Some jellyfish are venomous.
The toxin is delivered through stings.

✅ Some mushrooms are poisonous.
They are dangerous if consumed.

✅ Poison dart frogs are poisonous.
They do not need to bite or sting in order to be dangerous.

✅ A spider can be venomous.
✅ A mushroom can be poisonous.

The most common mistake is using poisonous for any dangerous animal.

But not every dangerous animal is poisonous.

If the animal harms you by injecting toxin, the more precise word is venomous.

For example:

❌ That snake is poisonous.
✅ That snake is venomous.

Another common mistake is thinking the two words are interchangeable. They are related, but they describe different methods of exposure.

Use this memory rule:

That is not a scientific definition in itself, but it is a very useful shortcut for remembering the distinction.

A simpler version: