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Webster 1913 Edition
Hypoptilum
‖
Hy-pop′ti-lum
,Noun.
pl. L.
Hypoptila
(#)
, E. Hypoptilums
(#)
. [NL., fr. Gr.
ὑπό
beneath + [GREEK] down.] (Zool.)
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
.