n. A ball or skein of thread or yarn.n. The thread or yarn that is wound into the form of a ball; thread in general.n. Hence Anything that guides or directs one in an intricate case; a guide or key to the solution of a puzzle or problem, or the unraveling of a plot or mystery: in allusion to the mythological story that Theseus was guided by a clue of thread through the Cretan labyrinth.n. A measure of yarn or hemp, 4,800 yards.n. Nautical, a lower corner of a square sail or the aftmost corner of a fore-and-aft sail.Nautical, to haul up to the yard (the lower corners of a topsail, topgallantsail, or royal) by means of the clue-lines: used with up.To direct, as by a clue or thread.