—n. 1. a feather.
2. a large, long, or conspicuous feather: the brilliant plume of a peacock. 3. a soft, fluffy feather: the plume of an egret. 4. any plumose part or formation.
5. a feather, a tuft of feathers, or some substitute, worn as an ornament, as on a hat, helmet, etc.
6. a feather or featherlike token of honor or distinction, esp. one worn on a helmet.
8. a vertically or longitudinally moving, rising, or expanding fluid body, as of smoke or water.
9. a visible pattern of smoke resulting from emissions from a stack, flue, or chimney.
10. Also called mantle plume.Geol.a deep-seated upwelling of magma within the earth's mantle. Cf. diapir.
—v.t. 1. to furnish, cover, or adorn with plumes or feathers.
2. (of a bird) to preen (itself or its feathers).
3. to feel complacent satisfaction with (oneself); pride (oneself) (often fol. by on or upon): She sat before the mirror, pluming herself upon her beauty.