1 : any of the secondary branches of a plumose organ especially of a crinoid. 2 : one of the ultimate divisions of a twice pinnate leaf.

What are pinnules used for?

a metal plate with a small hole in it, used as a sight in a quadrant.

What is a Pinule?

(ˈpɪnˌjul ) noun. any of the smallest divisions of a leaf which is doubly compound, esp. in ferns.