Vermin are small animals that cause problems for people, especially by spreading disease, destroying property, or eating stored food. Rats gnawing through walls, mice getting into grain supplies, and cockroaches infesting kitchens are classic examples of vermin. The word carries a strong sense of disgust and unwantedness.

Farmers might call rabbits vermin when they destroy crops, while city dwellers usually think of rats and mice. What counts as vermin depends on context: a rabbit might be a beloved pet in one house and vermin in a farmer's garden. The key is that these creatures are causing real damage or health risks, not merely being present.

People sometimes use vermin as an insult for humans they consider worthless or contemptible, though this is a harsh and dehumanizing way to speak. In stories, villains might refer to heroes as vermin to show their cruelty and contempt.

The word almost always appears in discussions of pest control or infestations. When someone discovers vermin in their home, they usually need to take action quickly to prevent the problem from getting worse.