HYPOPTILUM

‖Hy‐pop″ti‐lum (?), n.; pl. L. Hypoptila (#), E. Hypoptilums (#). [[NL., fr. Gr. υπὅ beneath + � down.]] (Zoöl.) 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.