pinnule noun. ['pɪnju:l] In sense 1 also (earlier) pinule. In senses 2, 3 also pinnula ['pɪnjʊlǝ], pl. -lae [-li:]. L16.
[Latin pinnula dim. of PINNA noun²: see -ULE.]
1. Either of two sights (usu. small perforated metal plates) at the ends of the alidade or index of an astrolabe, quadrant, or similar instrument. obsolete exc. Hist. L16.

2. Zoology. A part or organ resembling a small wing or fin, or a barb of a feather; spec. any of the jointed lateral branches along the arms of a crinoid. M18.

3. Botany. A subdivision of the pinna of a leaf, esp. of a fern; a leaflet; a lobe. L18.

■ pinnular adjective of or pertaining to a pinnule L19.

■ pinnulate adjective having pinnules E19.

[TahlilGaran] English Dictionary ▲