Английский Этимологический словарь - seat (1)

- "thing to sit on," 12c., from O.N. sжti "seat, position," from P.Gmc. *sжt-. The verb is from 1577. Meaning "posterior of the body" (the sitting part) is from 1607. O.E. had sжt "place where one sits in ambush," which also meant "residents, inhabitants," and is the source of the -set in Dorset and Somerset. Seat belt is from 1932, originally in airplanes.