English

Noun

fifth wheel ‎(plural fifth wheels)

1. 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.
2. A very large truck trailer; an 18-wheeler.
3. A very large trailer that is towed with a pickup truck.
4. A horizontal wheel or segment above the fore axle of a carriage and beneath the body, forming an extended support to prevent careening.
5. (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.

Synonyms

• (anything superfluous or unnecessary): third wheel, spare tool

Translations