1. Regarding young birds, a down feather which forms the natal plumage.
2. Feathers of nestlings; down feathers, or the down of newly hatched birds.
3. Etymology: from Greek neos, "new, young" + ptilon, "feather".....

The plumage of the newborn chick is downy, called neossoptile; the development which follows is termed teleoptile.

Juvenal plumage, is frequently distinct from that of the adult bird; is often drab, streaked, or spotted, and thus camouflages the young bird.