D defs.my
Entry 1 sense Webster, 1913

Hypoptilum

· Hy·pop·ti·lum · IPA
01 n. An accessory plume arising from the posterior side of the stem of the contour feathers of many birds; -- called also aftershaft. See Illust…
pl. Hypoptila, Hypoptilums ((#))
  1. 1.
    An accessory plume arising from the posterior side of the stem of the contour feathers of many birds; -- called also aftershaft. See Illust. of Feather.(Zool.) Also: aftershaft See: Feather