1. [n]  wingless usually flattened blood-sucking insect parasitic on warm-blooded animals
2. [n]  wingless insect with mouth parts adapted for biting; mostly parasitic on birds
3. [n]  any of several small insects especially aphids that feed by sucking the juices from plants
4. [n]  has a nasty or unethical character undeserving of respect

Louse
A wealthy, eccentric recluse addicted to heroin is completely dependent on his staff of servants and doctors. One of them--his valet, Herman Q. Louse--uncovers a conspiracy against his employer.

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1. \Louse\ (lous), n.; pl. {Lice} (l[imac]s). [OE. lous, AS.
   l[=u]s, pl. l[=y]s; akin to D. luis, G. laus, OHG. l[=u]s,
   Icel. l[=u]s, Sw. lus, Dan. luus; perh. so named because it
   is destructive, and akin to E. lose, loose.] (Zo["o]l.)
   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 ({P.
      vestimenti}), and the crab louse ({Phthirius pubis}), and
      many others. See {Crab louse}, {Dog louse}, {Cattle
      louse}, etc., under {Crab}, {Dog}, etc.
   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}.
   3. Any one of the numerous species of aphids, or plant lice.
      See {Aphid}.
   4. Any small crustacean parasitic on fishes. See
      {Branchiura}, and {Ichthvophthira}.
   Note: The term is also applied to various other parasites;
         as, the whale louse, beelouse, horse louse.
   {Louse fly} (Zo["o]l.), a parasitic dipterous insect of the
      group Pupipara. Some of them are wingless, as the bee
      louse.
   {Louse mite} (Zo["o]l.), 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.
   

2. \Louse\, v. t.
   To clean from lice. ``You sat and loused him.'' --Swift.