- modified down feathers that continually crumble at the tips, producing a fine powder that forms a bloom on the plumage of certain birds, as pigeons and herons.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for powder down
The powder-down patches of the oil bird are upon each side of the rump.
Powder-down feathers are degenerate down-feathers which appear to secrete a dry, waxy kind of powder.
There are several different kinds of feathers—contour feathers, semiplumes, down-feathers, filoplumes and powder-down.