pinion (n.1)

"wing joint, segment of a bird's wing," mid-15c., from Old French pignon "wing-feather, wing, pinion" (c. 1400), from Vulgar Latin *pinnionem (nominative *pinnio), augmentative of Latin pinna "wing" (see pin (n.)).

pinion (n.2)

"small wheel with teeth to gear with a larger one" (as in rack and pinion), 1650s, from French pignon "pinion" (16c.), literally "gable," from Old French pignon "pointed gable, summit," from Vulgar Latin *pinnionem, augmentative of Latin pinna "battlement, pinnacle" (see pin (n.)).

pinion (v.)

"disable by binding the arms," 1550s, older in English than literal sense "cut or bind the pinions (of a bird's wing) to prevent flying" (1570s); from pinion (n.1). Related: Pinioned.