Meaning of fifth wheel
- a horizontal ring or segment of a ring, consisting of two bands that slide on each other, placed above the front axle of a carriage and designed to support the forepart of the body while allowing it to turn freely in a horizontal plane.
- a similar device used as a coupling to connect a semitrailer to a tractor.
- a similar coupling between a heavy-duty pickup truck and a camping trailerthat extends over the bed of the truck.
- an extra wheel for a four-wheeled vehicle.
- a superfluous, unneeded, or unwanted person or thing: They enjoy making any outsider feel like a fifth wheel.