Fifth-wheel definition

An additional wheel carried on a four-wheeled vehicle as a spare.

noun

An extra and unnecessary person or thing.

noun

A wheel or portion of a wheel placed horizontally over the forward axle of a carriage to provide support and stability during turns.

noun

A similar device over the rear axle or axles of a tractor or pickup truck, serving as a coupling for a semitrailer.

noun

An unnecessary or superfluous person or thing.

noun

A horizontal wheel-like structure placed over the front axle of a carriage or wagon to support it on turns.

noun

A similar structure on the rear of the cab of a tractor-trailer, serving as a coupling for attaching the trailer.

noun

A type of trailer hitch, which consists of a horseshoe-shaped plate on a multi-directional pivot, with a locking pin to couple with the kingpin of a truck trailer.

noun

noun

A very large trailer that is towed with a pickup truck.

noun

(idiomatic) Anything superfluous or unnecessary.

As the third person along on their date, I felt like a fifth wheel.

I felt like a fifth wheel when they started giggling and making out during dinner.

noun

Other Word Forms

Singular:

fifth-wheel

Plural:

fifth-wheels