from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Any of numerous small, flat-bodied, wingless biting or sucking insects of the orders Mallophaga or Anoplura, many of which are external parasites on various animals, including humans.
  • n. Slang A mean or despicable person.
  • transitive v. Slang To bungle: loused the project; louse up a deal.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A small parasitic wingless insect of the order Phthiraptera.
  • n. A contemptible person; one who has recently taken an action considered deceitful or indirectly harmful.
  • v. To remove lice from the body of a person or animal; to delouse.

from the GNU version of the Collaborative International Dictionary of English

  • n. 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. See Crab louse, Dog louse, Cattle louse, etc., under crab, dog, etc.
  • n. 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.
  • n. Any one of the numerous species of aphids, or plant lice. See Aphid.
  • n. Any small crustacean parasitic on fishes. See Branchiura, and Ichthvophthira.
  • transitive v. To clean from lice.

from The Century Dictionary and Cyclopedia

  • n. An insect or other small arthropod (as a crustacean) that infests other animals or plants, or an animal resembling such parasites: a name for a great variety of small creatures.
  • n. Bird-lice are parasitic insects, of several hundred species, various genera, and several families, which some authors range with the foregoing in the order Hemiptera, but most place in the Pseudoneuroptera. They are known as the order or superfamily Mallophaga. They have mandibulate or biting mouth-parts, are wingless, and of very variable forms. They are by no means confined to birds, but infest mammals as well; almost every kind of bird and beast is infested by these creatures, sometimes several species to one host, and in such multitudes as to canse disease and death. Of these, such as infest domestic quadrupeds and birds belong to the genera Trichodectes, Docophorus, Nirmus, Goniocotes, Goniodes, Lipeurus, Trinotum, Colpopocephalum, Menopon, and Gyropus.
  • n. The beaver harbors a remarkable louse, Platypsyllus castoris, a degraded clavicorn beetle, so peculiar as to have been made type of an order, Achreioptera.
  • n. Insects have their own lice. Such are the bee-lice, or pupiparous dipterous insects of the family Braulidæ, order Diptera; and some of the lice of bats are similar dipterous insects, though wingless, of the family Nycteribiidæ. Bees, wasps, etc., are also infested by certain small parasitic heteromerous beetles in the form of lice, such as the wingless larvæ of Meloidæ, a species of which has been named Pediculus melittæ, and the whole family Stylopidæ. Insects affected by the latter are said to be stylopized. None of the foregoing lice are aquatic.
  • n. Fishes, marine mammals. crustaceans, etc., are infested by a great variety of small degraded crustaceans, collectively known as fish-lice or Ichthyophthira. Most of these belong to a class or order Epizoa or Siphonostoma, or Lernæoidea; a few are cirripeds, as Rhizocephala. Whale-lice are Cyamidæ. Carpice are Argulidæ.
  • n. Wood-lice are the terrestrial isopods of the family Oniscidæ, also called slaters, sow-bugs, etc. These are not parasites, but some of the aquatic isopods are fish-lice, as Cymothoidæ.
  • n. Plants are infested by multitudes of small plant-sucking hemipters, known as plant-lice, and formerly collectively termed Phytophthiria: as the aphids, Aphididæ, some of which are also called gall-lice; the psyllids, Psyllidæ, called flea-lice and jumping plant-lice; and the scale-insects or Coccidæ, some of which are also known as bark-lice.
  • n. Book-lice are pseudoneuropterous insects of the family Psocidæ, various species of which, as those of the genera Atropos and Clothilla, injure books.
  • n. Certain mites or acarids are sometimes called lice, as the harvest-ticks, known as red-lice, the itch-mite or itch-louse, etc. For further information, see the compounded words, and also the technical names.
  • To clean from lice.
  • A Middle English variant of loose.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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


Middle English, from Old English lūs.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Middle English lows(e), from Old English lūs, from Proto-Germanic *lūs (cf. West Frisian lûs, Dutch luis, Low Saxon (Low German) Luus, German Laus), from Proto-Indo-European *lewH- (cf. Welsh llau ("lice"), Tocharian B luwo, maybe Sanskrit यूका (yūkā)). (Wiktionary)


  • The bite of the louse is not virulent immediately after the infecting meal.

    Charles Nicolle - Nobel Lecture

  • Yes — you must answer for it all because you turned up like this, because I am a blackguard, because I am the nastiest, stupidest, absurdest and most envious of all the worms on earth, who are not a bit better than I am, but, the devil knows why, are never put to confusion; while I shall always be insulted by every louse, that is my doom!

    Notes from Underground

  • Asellus is very similar in size and shape to the common garden-louse, which is found in decaying wood.

    Amateur Fish Culture

  • Yes -- you must answer for it all because you turned up like this, because I am a blackguard, because I am the nastiest, stupidest, absurdest and most envious of all the worms on earth, who are not a bit better than I am, but, the devil knows why, are never put to confusion; while I shall always be insulted by every louse, that is my doom!

    Notes from the Underground

  • A louse is a louse and a bomb is a bomb, even though the cause you are fighting for happens to be just.

    Collected Essays

  • Although I'm strongly in favor of ending abusive relationships, part of me thinks you and the louse are the better-matched pair.

    Slate Magazine

  • Lice is the plural of louse, which is a small, quick, parasitic insect that cannot jump or fly, and the name for a louse's egg is a nit.

    Marshall Democrat-News Headlines

  • “Work was being rushed on” for the complete eradication of the clothing louse which is the carrier of the infection.

    The Better Germany in War Time Being some Facts towards Fellowship

  • Where a sick man had friends or comrades, of course part of their duty, in taking care of him, was to "louse" his clothing.

    Andersonville — Volume 2

  • Shallow no sooner corrects one mistake of Sir Hugh's, namely, 'louse' for 'luce,' a pike, but the honest Welchman falls into another, namely, 'cod' ( 'baccalà') 'Cambrice' 'cot' for coat.

    Literary Remains, Volume 2


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  • Ha! Whare ye gaun, ye crowlin ferlie?
    Your impudence protects you sairly,
    I canna say but ye strut rarely
    Owre gauze and lace,
    Tho' faith! I fear ye dine but sparely
    On sic a place.

    -Robbie Burns, "To a Louse"

    April 13, 2009