noun a down feather.
2. plumule ·pl of plumula.
3. plumule ·noun one of the featherlike scales of certain male butterflies.
4. plumule ·noun the aftershaft of a feather. ·see ·illust. under feather.
5. plumule ·noun the first bud, or gemmule, of a young plant; the bud, or growing point, of the embryo, above the cotyledons. ·see ·illust. of radicle.