What does louse mean?
A louse is a small, wingless insect that lives as a parasite on the hair or skin of humans and other mammals. The best-known varieties are the head louse, body louse, and pubic louse, which can cause itching and irritation, especially when several are present. The word is also used more broadly for closely related parasitic insects, such as those that infest animals. Its most memorable feature is its irregular plural: one louse becomes many lice, with the final “s” replaced by “ce.” In ordinary English, louse is relatively uncommon compared with the more familiar plural lice, but it remains the standard singular form. Related adjectives such as lousy are also used figuratively to describe something contemptible, unpleasant, or of poor quality.
nounA small, wingless parasitic insect that lives on the skin or hair of humans or other mammals. Louse commonly refers to the human body louse, but the term is also used for related species such as head and pubic lice.
- A parasitic insect that infests the hair, skin, or clothing of humans or other mammals.
- A louse that lives on the human head, especially the head louse.
- A louse that lives on the body, especially the body louse.
- A louse that inhabits the pubic region, especially the pubic louse.
"The child caught a head louse at school."
"She examined the child's hair for a louse after noticing persistent itching."
"The shelter provided clean clothing to help prevent the spread of body lice."
The plural is irregular: louse becomes lice, not louses. The plural can refer to several individual insects or, collectively, to an infestation.
"The nurse checked the pupils for lice before the class photos were taken."
The plural of louse is one of the most distinctive irregularities in English: one louse, but many lice.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Words that share this root
Related word forms
How louse is actually used
The standard plural is lice. In general use, louse usually refers to a particular kind of louse, while lice may refer to an infestation or to the insects collectively. The term is mainly literal, though related expressions can be used figuratively in informal speech.
Easily confused with louse
Louse is the singular form, while lice is the usual plural form.