powder down

短语

释义与例句

n.
  1. 1.

    A special type of down that occurs in a few groups of apparently unrelated birds. In some species, the tips of the barbules on the feathers disintegrate, forming fine particles of keratin; in others, powder grains come from cells that surround the barbules of growing feathers.

    不可数

    All parrots have powder down.