Definition of: louse

(lous) noun plural lice (līs)
1. A small, flat–bodied, wingless insect (order Anoplura) living as an external parasite on birds or mammals, especially the crab louse (Phthirus pubis) and the human body louse (genus Pediculus).
2. One of various other insects parasitic on other animals or plants, as the biting bird louse (order Mallophaga) and the plant louse. For illustrations see under INSECTS (injurious).
3. Slang A contemptible person.
—v.t. & v.i U.S. Slang To ruin; bungle: with up. [OE lūs]