Definitions of pinion:

• noun:   a gear with a small number of teeth designed to mesh with a larger wheel or rack
• noun:   wing of a bird
• noun:   any of the larger wing or tail feathers of a bird
• verb:   cut the wings off (of birds)
• verb:   bind the arms of
• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #13681)