an individual seat with a rounded or contoured back, as in some automobiles and airplanes, often made to fold forward.
a seat in a car, aircraft, etc, having curved sides that partially enclose and support the body
Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
The tractor had an enclosed cab and a bucket seat without seatbelts.
Two main frame types have evolved so far, the cage seat and the bucket seat.
Since then the three standard swings and one bucket seat swing were removed.
Those that used the simulator found themselves in a small trailer next to the track, buckled into a bucket seat.