1. A surface upon which another part rests or seats. Example: valve seat is matched surface upon which valve face rests. See valve seat .
2. Minor wearing of the piston ring surface during initial use. Rings then fit or seat properly against the cylinder wall .
3. The cushions on which the driver and passengers rest. Also see bench seat , bucket seat , power seat , rumble seat , saddle , and split bench seat .
4. A metering control that is regulated by a needle . See needle and seat .