n.; pl. Lice [ OE. lous, AS. lūs, pl. l&ymacr_;s; akin to D. luis, G. laus, OHG. lūs, Icel. lūs, Sw. lus, Dan. luus; perh. so named because it is destructive, and akin to E. lose, loose. ] (Zool.) 1. Any one of numerous species of small, wingless, suctorial, parasitic insects belonging to a tribe (Pediculina), now usually regarded as degraded Hemiptera. To this group belong of the lice of man and other mammals; as, the head louse of man (Pediculus capitis), the body louse (Pediculus vestimenti), and the crab louse (Phthirius pubis), and many others. See Crab louse, Dog louse, Cattle louse, etc., under Crab, Dog, etc. [ 1913 Webster ]

2. Any one of numerous small mandibulate insects, mostly parasitic on birds, and feeding on the feathers. They are known as Mallophaga, or bird lice, though some occur on the hair of mammals. They are usually regarded as degraded Pseudoneuroptera. See Mallophaga. [ 1913 Webster ]

3. Any one of the numerous species of aphids, or plant lice. See Aphid. [ 1913 Webster ]

4. Any small crustacean parasitic on fishes. See Branchiura, and Ichthvophthira. [ 1913 Webster ]

☞ The term is also applied to various other parasites; as, the whale louse, beelouse, horse louse. [ 1913 Webster ]

Louse fly (Zool.), a parasitic dipterous insect of the group Pupipara. Some of them are wingless, as the bee louse. --
Louse mite (Zool.), any one of numerous species of mites which infest mammals and birds, clinging to the hair and feathers like lice. They belong to Myobia, Dermaleichus, Mycoptes, and several other genera. [ 1913 Webster ]

v. t. To clean from lice. “You sat and loused him.” Swift. [ 1913 Webster ]

n. (Bot.) Any species of Pedicularis, a genus of perennial herbs. It was said to make sheep that fed on it lousy. [ 1913 Webster ]

Yellow lousewort, a plant of the genus Rhinanthus. [ 1913 Webster ]