What does "plumage" mean?

Plumage: The entire clothing of a bird. Note: It consist of the contour feathers, or the ordinary feathers covering the head, neck, and body; the tail feathers, with their upper and lower coverts; the wing feathers, including primaries, secondaries, and tertiaries, with their coverts; and the down which lies beneath the contour feathers. See Illust. under Bird.