A louse is a small wingless insect that lives on skin and hair. A head louse, lice in the class, check for a louse.
Head lice have nothing to do with dirt and spread by head-to-head contact, which is why they run through clean classrooms. The plural is lice. Wet combing removes them without chemicals. As slang, a louse is a contemptible person.
1nounlouseA small wingless insect that lives on skin and hair.
“The school nurse found a louse in the boy's hair.”
louse is an insect.
Old English lus names the insect, from a Germanic root going back to Proto-Indo-European. The plural lice comes from an old vowel change.
Middle English
lous
English, today
louse
From Middle English lous. From Middle English lous, lows, lowse, from Old English lūs, from Proto-West Germanic lūs, from Proto-Germanic lūs, from Proto-Indo-European lewH-. Cognate with West Frisian lûs, Dutch luis, German Low German Luus, German Laus, Danish, Norwegian Bokmål, Norwegian Nynorsk and Swedish lus, Faroese and Icelandic lús; also Welsh llau (“lice”), txb luwo, maybe Sanskrit यूका.
Etymology from Wiktionary, CC BY-SA