louse

American  

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

noun

plural

lice, louses

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.

---

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

---

verb

1. to remove lice from

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

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

Example Sentences

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

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

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

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

From "The Teacher’s Funeral" by Richard Peck