louse
Americannoun
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any small, wingless insect of the order Anoplura sucking louse, parasitic on humans and other mammals and having mouthparts adapted for sucking, as Pediculus humanus humanus body louse or Pediculus humanus capitis head louse and Phthirius pubis crab louse, or pubic louse.
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any insect of the order Mallophaga bird louse, biting louse, or chewing louse, parasitic on birds and mammals, having mouthparts adapted for biting.
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Slang. a contemptible person, especially an unethical one.
verb (used with object)
verb phrase
noun
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any wingless bloodsucking insect of the order Anoplura: includes Pediculus capitis ( head louse ), Pediculus corporis ( body louse ), and the crab louse, all of which infest man
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any wingless insect of the order Mallophaga, such as the chicken louse: external parasites of birds and mammals with biting mouthparts
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any of various similar but unrelated insects, such as the plant louse and book louse
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slang an unpleasant or mean person
verb
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to remove lice from
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slang (foll by up) to ruin or spoil
Other Word Forms
Noun Inflected Forms
Etymology
Origin of louse
First recorded before 900; 1910–15 louse for def. 4; Middle English lous(e), luse, plural lise, lice; Old English lūs, plural lȳs; cognate with Dutch luis, German Laus, Old Norse lūs
Explanation
A louse is a tiny insect that lives on the skin of animals and people. If you find a louse in your hair, you'll have to treat your scalp to get rid of any of its friends that might still be lurking there. Since they tend to travel in groups, the plural form of louse, lice, is much more common than the singular. Lice are small parasites that live on skin cells, blood, or other tiny bits of some host animal. If you're the host animal, you'll probably have an itchy head, and anyone who borrows your pillow or wears your hat will likely get lice too. A louse, informally, is also "an obnoxious person."
Vocabulary lists containing louse
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
We get hints that Paul’s previous self was a louse, but Holland’s smile is so soft that it’s hard to believe he was ever a nasty, selfish jerk.
From Los Angeles Times ● Mar. 12, 2025
A genetic analysis based on louse DNA revealed the existence of two distinct clusters of lice that rarely interbred.
From Science Daily ● Nov. 8, 2023
“We can see the louse DNA reflected in our own history.”
From Science Magazine ● Nov. 7, 2023
Only one animal parasite, the pygmy hog-sucking louse, is currently included on the International Union for Conservation of Nature’s Red List of Threatened Species, and none are included on the U.S.
From Scientific American ● May 18, 2022
Sam Westing, the louse, has cheated him again.
From "The Westing Game" by Ellen Raskin
We get a clear-eyed look at disgust, a nearly universal human response to the likes of maggots, cockroaches, ticks, leeches, slugs and lice.
From The Wall Street Journal ● Apr. 30, 2026
W. H. Auden once wrote of a miserable Roman soldier guarding a cold, rain-soaked wall in northern Europe, mentioning "lice in my tunic and a cold in my nose."
From Science Daily ● Dec. 21, 2025
Hundreds of parasites have the ability to infect humans, including lice, mites and ticks.
From Salon ● May 18, 2025
She was described as gaunt, with dark rings under her eyes and the worst case of head lice an expert had seen in her 30-year career.
From BBC ● Jan. 27, 2025
That is why Miss Charlotte Mortimer had sent the herbal poultice; at Swanburne her headmistress used to apply it to Penelope’s head every six weeks or so to maintain scalp health and repel lice.
From "The Incorrigible Children of Ashton Place: Book I: The Mysterious Howling" by Maryrose Wood
In the album’s liner notes, the band offers “special thanks from these louses to our spouses for letting us make all this racket around the houses.”
From Seattle Times ● Jan. 13, 2022
In layman's terms, it's a hotel for bugs, the smallest of the small—wood louses, millipedes, and anything else that could find its way in.
From Golf Digest ● Oct. 16, 2013
Maybe all her friends are a bunch of louses and she should cut her losses and not invite them to the wedding.
From Slate ● Jan. 22, 2013
How long can it be before she’s emotionally manipulated, professionally undermined, romanced by louses and ruined for life?
From New York Times ● Jan. 3, 2012
"It shows his mind's troubled, for he usually louses at six."
From Sentimental Tommy The Story of His Boyhood by Barrie, J. M. (James Matthew)
No 404 notice, no “your internet connection is loused up” message — and especially, no Wordle.
From The Verge ● Feb. 16, 2022
Despite his job problems, he is sticking with Carter "even though he loused up the economy."
From Time Magazine Archive
One paper quoted Lana's apology: "MGM loused it up."
From Time Magazine Archive
Airline schedules are loused up, somebody is shouting at somebody else who can't help the situation, a lot of money has been lost, and about two dozen people are caught up in a cybernetic tangle.
From Time Magazine Archive
It seemed she had two or three daughters, and that year they were all going to be debutantes, only she had loused up their debutante party by signing herself into the asylum.
From "The Bell Jar" by Sylvia Plath
“I’m lousing up my moon picture,” Messuri said.
From The New Yorker ● Jul. 15, 2019
“A couple of generations after I’m dead and gone,” he likes to say, “the Ph.D.’s will start lousing through my work. Just imagine their surprise. ‘
From The New Yorker ● Jul. 27, 2015
Silver, who is called only Silver, perhaps because no one respects him enough to use his full name, has gone through life lousing things up.
From New York Times ● Aug. 15, 2012
Does she think he regrets lousing up their marriage?
From The Guardian ● Oct. 22, 2010
It was nearing "lousing time" and Mrs. Sinclair was busy getting the dinner ready, and water boiled to wash the men coming in from the pit, and she wondered how Robert would take the news.
From The Underworld The Story of Robert Sinclair, Miner by Welsh, James C.
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
