From Old English 'lus' and PIE *lus- — virtually unchanged across 6,000 years, present in nearly every IE branch.
A small wingless parasitic insect that lives on the skin or in the hair of its host, feeding on blood or skin debris. Plural: lice.
From Old English 'lūs' (louse), from Proto-Germanic *lūs, from PIE *lūs- (louse). This is one of the oldest continuously attested words in the Indo-European family — virtually every branch preserves a cognate, suggesting that the PIE-speaking peoples were familiar with lice and had a word for them at least 6,000 years ago. The word has been remarkably stable: the modern pronunciation is not far from the reconstructed Proto-Indo-European form. Key roots: *lūs- (Proto-Indo-European: "louse").