Vermin (noun)

1. Small animals or insects that are harmful to plants, animals or humans, especially those regarded as pests.
2. People or things that are regarded as worthless or contemptible.

Origin:

From the middle english word "vermin" meaning "small harmful animals or pests".

Examples:

1. Rats and mice are common examples of vermin.
2. Insects such as termites and ants are also considered vermin.
3. The farmer had to use pesticides to get rid of the vermin in the fields.
4. He called his opponents "vermin" who were trying to destroy his reputation.
5. Vermin such as cockroaches can carry and spread diseases.