Definition of louse in English:



  • 1Either of two small wingless parasitic insects that live on the skin of mammals and birds.

    • ‘The gold standard for diagnosing head lice is finding a live louse on the head, which can be difficult.’
    • ‘A strong solution of it can even remove lice or other skin parasites.’
    • ‘As earlier research had shown, they found a major split among lice species that live on apes and on monkeys and other primates.’
    • ‘Villagers also cited skin, lice, and saliva as carriers of the disease.’
    • ‘There are also flies whose larvae develop only in the tracheal passages of red kangaroos and lice that live in the throat pouches of cormorants and pelicans.’
    • ‘Head lice are insects that live on the scalp and neck.’
    • ‘The main effect of feather lice on their bird hosts is feather damage.’
    • ‘As a result of their cramped conditions, diseases such as eye cataracts and parasitic sea lice are rife, the group claims.’
    • ‘Only the presence of live lice can confirm diagnosis of active infection.’
    • ‘You only treat for head lice if you find live lice in the hair.’
    • ‘Head lice are small, wingless insects that can get on the hair and scalp of humans.’
    • ‘Before treatment, live lice must be identified under a magnifying glass, which is best done when the hair is wet.’
    • ‘Some germs rely on insects - such as mosquitoes, fleas, lice or ticks - to move from host to host.’
    • ‘Presumably mineral oil is acting like petroleum jelly to smother the live lice and loosen nits.’
    • ‘Treatment should be repeated after seven to 10 days if live lice are present.’
    • ‘Petroleum jelly, mayonnaise and mineral oil seem to smother live lice.’
    • ‘Beds were made from straw, which of course is a home for insects of all kinds, particularly fleas, lice, and tics.’
    • ‘Control of poultry lice requires treating the birds since lice remain on the bird throughout its life.’
    • ‘Head lice are insects living on the human scalp and feeding on blood.’
    • ‘I haven't seen a live louse on her head since last Wednesday.’
    1. 1.1Used in names of small invertebrates that parasitize aquatic animals or infest plants, e.g. fish louse.
      • ‘Stalked barnacles and whale lice often attach to the exposed teeth..’
      • ‘It is the realm of periwinkles, limpets, rock lice, and barnacles.’
      • ‘Sea trout numbers collapsed in 1989 with many sea trout caught in the net heavily infested with sea lice.’
      • ‘They are also hosts to a number of blood parasites and feather lice.’
      • ‘Sea spiders and sea lice have a cavity of body fluid as salty as the sea itself.’
  • 2informal A contemptible or unpleasant person.

    • ‘Since his original plan of using leftover roach motels now seems impractical, Jack must devise a better means of sending these unlicensed louses back to where they belong.’
    • ‘He said that, among the others using that network, there could be louses looking for their next attack target.’
    • ‘All of these characters - if we can indeed call them that - are despicable louses that lie, cheat, and backstab each other in the name of comedy and TV ratings.’
    • ‘The louses are just plain nasty drivers who don't give a damn about anyone but themselves.’
    • ‘His characters were cads, letches, and leering louses, but they effectively tapped a bit of that inappropriate urge in us all.’
    scoundrel, villain, rogue, rascal, brute, animal, weasel, snake, monster, ogre, wretch, devil, good-for-nothing, reprobate, wrongdoer, evil-doer
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  • 1informal Spoil or ruin something.

    ‘he loused up my promotion chances’
    • ‘Let's not louse it up by letting someone else take over and make the rules for us.’
    • ‘Sorry for being such a dope but this is my first dedicated server and I prefer not to louse it up right off!’
    • ‘Your summer has been a colossal mess, but other folks have been lousing things up, too.’
    • ‘If he loused it up in any way, everybody would laugh and they would do it over again.’
    • ‘The thing that I really heard was ‘Let's not louse it up with a lot of psychobabble.’’
    • ‘They then took this cleaner to their design team who loused it up for probably for more money!’
    • ‘Rebecca has an unerring ear for the ways mismatched people relate, an open heart for the ways they louse things up.’
    • ‘The assumption, as is often the case with this cretaceous era of computer software, is that someone else has loused it up for them.’
    • ‘But then she had to go and louse it up by acting like a damn pop star.’
    • ‘However, the mechanic loused it up, but tried to convince me that that was as good as those engines could get.’
    • ‘The brain trust decided to ‘fix’ it after that one year and loused it up royally.’
    • ‘The film really tries to delve into the Romulus / Remus iconography of brotherhood, but louses it up tremendously.’
    • ‘Without had evidence in front of me, I'm inclined to believe older browsers like that would louse it up.’
    • ‘They take perfectly good water and louse it up with kiwi and strawberry.’
    • ‘This could have been excellent and by far the best version of the game, so it's a shame they loused it up so badly.’
    • ‘Too bad they loused it up with predictable plot elements and assorted screwball humor.’
    • ‘And I can see why he probably said that - the event should garner some positive local press for the party and they might not want to louse it up with an incident involving police.’
    wreck, ruin, spoil, disrupt, undo, upset, play havoc with, make a mess of, put an end to, end, bring to an end, put a stop to, terminate, prevent, frustrate, blight, crush, quell, quash, dash, scotch, shatter, vitiate, blast, devastate, demolish, sabotage, torpedo
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  • 2archaic Remove lice from.

    • ‘When the girl and the lion first appear in the tale we are told that she is lousing him, which illustrates the bond between them.’
    • ‘The grandmother began lousing him again and soon he was asleep and snoring loud enough to rattle the windows.’
    • ‘They were lousing each other; and it surprised us that they did not discontinue their work + as we entered.’


Old English lūs, (plural) lȳs, of Germanic origin; related to Dutch luis, German Laus.