1. the long plumes of a heron in the breeding season. 2. A large feather or cluster of feathers worn as an ornament or symbol of rank, as on a helmet. 3. A token of honor or achievement. 4. a plume of smoke. 5. A space in air, water, or soil containing pollutants released from a point source. 6. An upwelling of molten material from the earth's mantle. 7. To decorate, cover, or supply with or as if with plumes. 8. To smooth (feathers); preen. 9. plumed himself on his victory.
