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

The human louse is a wingless, blood-sucking parasite that lives its entire life on its host.

From Science Daily ● Nov. 8, 2023

Along our evolutionary journey from monkey-like primates to bipedal apes to big-brained humans, we have had the company of an extraordinarily loyal companion: Pediculus humanus, otherwise known as the human louse.

From New York Times ● Nov. 8, 2023

“We can see the louse DNA reflected in our own history.”

From Science Magazine ● Nov. 7, 2023

I had probably been too filthy for any self-respecting louse to take up residence.

From "The Name of the Wind" by Patrick Rothfuss

These include scabies – caused by mites, lice and bed bugs.

From BBC ● May 2, 2026

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

The latter is transmitted by lice and produces alternating periods of fever and recovery.

From Science Daily ● Oct. 26, 2025

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

I didn’t care if it was a caterpillar or a bramble or lice.

From "The Line Tender" by Kate Allen

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

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

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

From Time Magazine Archive

One paper quoted Lana's apology: "MGM loused it up."

From Time Magazine Archive

In New Ulm, Minn., police forbade truckers to park livestock near churches when congregations complained that off-key moos loused up the hymns.

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