louse

American  

[laus, laus, lauz] / 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

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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

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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

This allowed them to identify traces of several pathogens, including Yersinia pestis, the bacterium responsible for plague, and Borrelia recurrentis, which causes louse borne relapsing fever.

From Science Daily ● Jul. 8, 2026

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

“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

She’d skin a louse for its hide and tallow.

From "The Teacher’s Funeral" by Richard Peck

The idea is to keep out sea lice, which mostly live near the surface.

From The Wall Street Journal ● Oct. 20, 2026

To tackle sea lice, the company has deployed underwater cameras that automatically count the number of parasites on each fish.

From The Wall Street Journal ● Oct. 20, 2026

Still others described unexplained rashes, outbreaks of diarrhea and infestations of lice, among a host of other maladies for which many said they were offered only Tylenol or allergy medication.

From Los Angeles Times ● Jul. 24, 2026

This suggests that immersion in hot water may interfere with lice activity or where they lay their eggs.

From Science Daily ● Mar. 3, 2026

The free ride may be provided by mosquitoes, fleas, lice, or tsetse flies that spread malaria, plague, typhus, or sleeping sickness, respectively.

From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond

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

I understand his impulse: Banish the cad to Borneo along with all the other louses, including Arnold Schwarzenegger and John Edwards.

From New York Times ● Jun. 2, 2011

"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

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

If we hadn't got loused up we'd of had 50 percent.

From Time Magazine Archive

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

From Time Magazine Archive

He could hardly believe he had loused things up quite so badly.

From "Middlesex: A Novel" by Jeffrey Eugenides

“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 James C. Welsh

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