louse

American  

[lous, lous, louz] / laʊs, laʊs, laʊz /

noun

• lice,
  plural
• louses
  plural

1. 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.

2. any insect of the order Mallophaga bird louse, biting louse, or chewing louse, parasitic on birds and mammals, having mouthparts adapted for biting.

3. plant louse.

4. Slang. a contemptible person, especially an unethical one.

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verb (used with object)

loused, lousing

1. to delouse.

verb phrase

1. louse up to spoil; botch.

   Miscasting loused up the movie.

louse British  

/ laʊs /

noun

1. 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

2. any wingless insect of the order Mallophaga, such as the chicken louse: external parasites of birds and mammals with biting mouthparts

3. any of various similar but unrelated insects, such as the plant louse and book louse

4. slang an unpleasant or mean person

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verb

1. to remove lice from

2. slang (foll by up) to ruin or spoil

Other Word Forms

Noun Inflected Forms

• lice
  plural
• louses
  plural

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."

Example Sentences

See Examples For:

louse lice louses loused lousing

Victor was a louse in his first marriage and father of the year in his second.

From Los Angeles Times ● Feb. 28, 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

Odenkirk, in particular, is willing to go full louse.

From New York Times ● Jan. 26, 2023

Hooke had shown that the louse was every bit as complicated a creature as a lizard.

From "The Invention of Science" by David Wootton

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

Monkeys that soaked in the warm water had different patterns of lice on their bodies and differences in certain gut bacteria.

From Science Daily ● Mar. 3, 2026

They picked them up from school, held the flashlight while I checked for lice, assisted them with math homework and attended their school performances.

From Los Angeles Times ● May 20, 2025

Hundreds of parasites have the ability to infect humans, including lice, mites and ticks.

From Salon ● May 18, 2025

When people took sick, their temperatures rose and caused the body lice to seek more hospitable abodes.

From "Innumeracy: Mathematical Illiteracy and Its Consequences" by John Allen Paulos

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 J. M. (James Matthew) Barrie

No 404 notice, no “your internet connection is loused up” message — and especially, no Wordle.

From The Verge ● Feb. 16, 2022

National ads . . . are all loused up with overexcited, overeager, overhappy faces.

From Time Magazine Archive

He has called Adlai Stevenson "completely inept," castigated Averell Harriman as the man "who loused up Laos," described Pierre Salinger as "the thinking man's filter."

From Time Magazine Archive

Despite his job problems, he is sticking with Carter "even though he loused up the economy."

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

Yesterday, you were accusing me of being some kind of psycho who was lousing up the expedition out of pure—pure—" he searched for a term currently in use in mentology—"demonia.

From The Planet with No Nightmare by Jim Harmon