Meaning of louse in English. louse. noun [ C ] us / laʊs / uk / laʊs / plural lice. Add to word list Add to word list. a very small insect that lives on the bodies or in the hair of people and animals. IMNATURE/iStock/Getty Images Plus/GettyImages. 1. plural lice / ˈlaɪs/ : a type of small insect that lives on the bodies of people or animals. a problem with head lice. 2. informal plural louses : a bad or cruel person. Her ex-husband is a real louse. 2 louse / ˈ laʊs/ verb. louses; loused; lousing. VWgHx.