2 Ornithology A bird’s down feather, numbers of which form an insulating layer under the contour feathers.
More example sentences
- The second group includes down feathers, or plumules, which are softer and shorter than contour feathers.
- Geese are larger than ducks so their down plumules are larger and typically geese from colder climates such as central and northern Europe have the largest plumules.
Definition of plumule in:
- The US English dictionary