fifth wheel

American  

[fifth weel, hweel, fith] / ˈfɪfθ ˈwil, ˈʰwil, ˈfɪθ /

noun

1. 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 carriage body while allowing it to turn freely in a horizontal plane.

2. a similar device used as a coupling to connect a semitrailer to a tractor.

3. a similar coupling between a heavy-duty pickup truck and a camping trailer fifth-wheel trailer that extends over the bed of the truck.

4. an extra wheel for a four-wheeled vehicle.

5. third wheel.

   I decided not to go along on the canoe trip with him and his friends—I’d just be a fifth wheel.

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fifth wheel British  

noun

1. a spare wheel for a four-wheeled vehicle

2. 1. the coupling table of an articulated vehicle

   2. a steering bearing that enables the front axle of a horse-drawn vehicle to rotate relative to the body

3. a superfluous or unnecessary person or thing

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fifth wheel Cultural  

1. A hanger-on; a person who serves no function: “The vice president felt like a fifth wheel after his exclusion from the committee.”

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fifth wheel Idioms  

1. An extra and unnecessary person or thing, as in He was the only one without a date, so he felt like a fifth wheel. This expression, which alludes to an unneeded wheel on a four-wheel vehicle, may have originated as long ago as 1631, when Thomas Dekker wrote Match Me in London: “Thou tiest but wings to a swift gray Hounds heel, And addest to a running Chariot a fifth wheel.”

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Etymology

Origin of fifth wheel

First recorded in 1870–75

Example Sentences

“Before the fire you could park a fifth wheel anywhere. Now they’ve made laws,” Munjar said.

From Los Angeles Times • Aug. 20, 2023

The son attempted to back his truck and fifth wheel trailer from the street up the incline of the driveway, Huserik said.

From Seattle Times • Oct. 21, 2021

“Gene therapy is taking a fifth wheel and putting it somewhere on the car and hoping it runs. Gene editing is repairing the flat.”

From Scientific American • Jul. 17, 2021

“The fifth wheel loses his air conditioning, and he drives on,” Freddy said, marveling at people’s stupidity.

From Washington Post • Oct. 8, 2020

I’m in no hurry to go in there to be a fifth wheel, treated like I’m hopelessly out of it, old-fashioned and humorless, by the freewheeling Richard.

From "Orphan Train" by Christina Baker Kline