plumule

A down feather.

The young shoot of a plant embryo above the cotyledons, consisting of the epicotyl and often of immature leaves.

In ornithology, a down-feather; a feather of plumulaceous structure throughout.

In entomology: A little plume-like organ or ornament.

One of the peculiar obcordate scales found on the wings of certain lepidopterous insects, as Pieridæ.