rectrix

[ rek-triks ]

/ ˈrɛk trɪks /

one of the tail feathers of a bird controlling direction during flight.

Origin of rectrix

1605–15; < Latin rēctrīx, feminine of rēctor rector

rec·tri·cial

[rek-trish-uh l] /rɛkˈtrɪʃ əl/, adjective

Quill feathers of the wing (remiges) and tail (rectrices); the former are attached to the hand and forearm.

The New Gresham Encyclopedia |Various
Slightly elevated remiges and rectrices, still in the sheath, were visible on the ninth day.

The Postnatal Development of Two Broods of Great Horned Owls |Donald F. Hoffmeister
Nasal depression more than half as long as maxilla; rectrices twelve.

British Birds in their Haunts |Rev. C. A. Johns
The last six or seven caudal vertebrae coalesce into the pygostyle, an upright blade which carries the rectrices.

Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 7 |Various

Rectrices beneath yellowish grey, darker toward the tips of the longer feathers.

Extinct Birds |Walter Rothschild

rectrix

/ (ˈrɛktrɪks) /

any of the large stiff feathers of a bird's tail, used in controlling the direction of flight

rectricial (rɛkˈtrɪʃəl), adjective

C17: from Late Latin, feminine of rector governor, rector