Louse (noun)

1. A small wingless insect that lives on the skin and hair of humans and animals, causing itching and skin irritation.
2. An unwanted and unpleasant person, typically one who is dirty or parasitic.
3. A contemptible or worthless person.

Origin:

Old english lūs, of germanic origin; related to dutch luis and german laus.

Examples:

1. The lice infestation was treated with medicated shampoo.
2. The lice were found in the child's hair.
3. The lice were a common problem in crowded conditions.
4. He was called a louse for cheating on his wife.
5. The louse was a parasite that feeds on human blood.