hypoptilum

Hy*pop"ti*lum, n.; pl. L. Hypoptila, E. Hypoptilums. Etym: [NL., fr. Gr. (Zoöl.) Defn: 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.

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