- IPA[ˌfi(f)TH ˈ(h)wēl]
- an extra wheel for a four-wheeled vehicle.；a superfluous person or thing.
noun: fifth wheel, plural noun: fifth wheels
- 1. an extra wheel for a four-wheeled vehicle.
- ▪ informal a superfluous person or thing.
- 2. a coupling between a trailer and a vehicle used for towing.
- ▪ a trailer with accommodations for camping out.
- ▪ historical a horizontal turntable over the front axle of a carriage as an extra support to prevent it tipping.