Bugs that live in human hair, plural of louse. Contrary to popular belief, you don't have to be unclean to get them, you just have to come in contact with one of them. Common ways that lice are spread are through hats, combs, and any shared items touching a carrier's head. Their eggs cling to your strands of hair, making it relatively hard to remove them. Special shampoo is the best method of curing an infestation.
Junior had lice last year; he told me it wasn't fun.