louse

noun pl. lice

1. 1. any of an order (Anoplura) of small, flat, wingless insects with sucking mouthparts, parasitic on the skin or hair of humans and some other mammals; esp., the human (Pediculus humanus corporis) and (P. h. capitis)
   2. any of various arthropods that suck blood or juice from other animals or plants
2. bird louse
3. any of various other small insects, arachnids, and crustaceans that are not parasitic, as the book louse or wood louse
4. Slang a person regarded as mean, contemptible, etc.

transitive verb loused, lousing