pinion

/ˈpɪnjən/

/ˈpɪnjɪn/

Other forms: pinions; pinioned; pinioning

Many cars use rack-and-pinion steering, in which the steering wheel turns a small-toothed pinion gear, which engages the larger rack that turns the car's wheels.

Pinions make steering easy and smooth. This is true for cars as well for birds — pinion can also refer to a bird's wing or a large wing feather. Pinion comes to English through Old French, but the word ultimately derives from Latin pinna, meant both "feather" and "battlement."

Definitions of pinion

1. noun

   wing of a bird
   synonyms: pennon

   type of:

   wing

   a movable organ for flying (one of a pair)
2. noun

   any of the larger wing or tail feathers of a bird
   synonyms: flight feather, quill, quill feather

   types:

   primary, primary feather, primary quill

   one of the main flight feathers projecting along the outer edge of a bird's wing

   tail feather

   feather growing from the tail (uropygium) of a bird

   sickle feather

   one of the long curved tail feathers of a rooster

   type of:

   feather, plumage, plume

   the light horny waterproof structure forming the external covering of birds
3. verb

   cut the wings off (of birds)
   type of:

   disable, disenable, incapacitate

   make unable to perform a certain action
4. verb

   bind the arms of
   synonyms: shackle

   type of:

   confine, hold, restrain

   to close within bounds, limit or hold back from movement
5. noun

   a gear with a small number of teeth designed to mesh with a larger wheel or rack
   types:

   lantern pinion, lantern wheel

   a small pinion having cylindrical bars instead of teeth, used chiefly in inexpensive clocks

   type of:

   cogwheel, gear, gear wheel, geared wheel

   a toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion