n. In architecture, the triangular surface of a pendentive.n. A plume as worn in a hat or helmet or in a woman's hair; especially, in medieval armor, a massive group of feathers set erect, often used as a heraldic bearing.n. In zoology, a tuft, bunch, or cluster of hairs, feathers, or the like; a scopula; a panicle.n. In astronomy, a tuft-like solar protuberance of eruption.