clue

Origin

Variant of clew (“a ball of thread or yarn”), from Middle English clew, clewe, clowe, clue, clwe, clyw, clywe, from Old English clēowen, clīewen, clīowen, clīwen, clȳwe, clȳwen (“ball, sphere; skein”), from Proto-West Germanic *kliuwīn (“ball, clump”), from Proto-Germanic *kliuwīną, *klewô (“bale, ball, clump, mass”), from Proto-Indo-European *glew- (“to ball up, clump together; lump, swelling”). Sense evolution with reference to the one which the mythical Theseus used to guide him out of the Minotaur's labyrinth. More at clew.