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

Initially, we can’t wait for Iacono’s louse to get eaten but we come to treasure his comic relief, particularly when Xavier wanders off to relieve himself next to a nest of velociraptors.

From Los Angeles Times ● Jun. 30, 2025

These people then spread south into Central America, where modern louse populations today still retain a genetic signature from their distant Asian ancestors.

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

The lion grunted and lay still while the hare pretended to search for another louse.

From "The Girl Who Married a Lion: and Other Tales from Africa" by Alexander Mccall Smith

She also taught the fathers basic hair-care techniques, including shampooing, detangling, checking for lice and how to tie ponytails and braids.

From Los Angeles Times ● Jun. 19, 2026

While starving and battling lice, the young women distracted themselves by fantasizing about food.

From The Wall Street Journal ● May 14, 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

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

From Salon ● May 18, 2025

“That’s sufficient only if it keeps her head free of lice and fleas,” the principal replied.

From "Tasting the Sky" by Ibtisam Barakat

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

These include ensuring legal protections for endangered louses and nematodes, building parasitism into the K-12 curriculum, and getting the public not just mildly curious but “enthusiastic” about parasites.

From Washington Post ● Dec. 14, 2020

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

The dozen white louses do become an old coat well; it agrees well, passant; it is a familiar beast to man, and signifies love.

From The Merry Wives of Windsor The Works of William Shakespeare [Cambridge Edition] [9 vols.] by John Glover

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

From The Verge ● Feb. 16, 2022

But she adds with pride: "Nobody ever got loused up in the Venice."

From Time Magazine Archive

What finally "loused up" Willie was a big, quiet civil servant named Elmer.

From Time Magazine Archive

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

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

You are unsatisfied with it, because—uh—your peculiar talent is lousing up your profession.

From The Animated Pinup by Lewis Parker