Perhaps you’re the singleton hanging out with a couple. Or the third friend hanging out with two besties. Or worst of all, maybe you’re the office junior sat between two managers on the work night out. 

No matter what potentially awkward situation you’ve found yourself in, the chances are that at some time you’ve been the proverbial third wheel—the unnecessary or unwanted hanger-on, who finds themselves stuck alongside a much more fitting or natural pair. But how did this awkwardly unwelcome “third” come to be referred to as a “wheel”? 

EARLY 18TH CENTURY

For such a modern-sounding phrase, the notion of an unnecessary “third wheel” dates all the way back to the early 18th century. The Oxford English Dictionary has unearthed its earliest known record of this expression in a Scots pastoral comic play, called “The Gentle Shepherd,” that was written by the Scottish writer and poet Allan Ramsay in 1725. In the play, the eponymous shepherd Patie jokes of relocating to France, only to return to Scotland as a foppish dandy or “some petted thing’s dull slave,” who spends his days earning a “few bags of cash” that he would “nae mair need nor carts do a third wheel.” Or in other words, he would return as a gentleman who is so wealthy that he wouldn’t need the money he earns any more than a two-wheeled farming cart requires a third wheel. 

Whether Ramsay invented this image for his comedy, or the jokey metaphor was already in wider use before he set it down in print 300 years ago, is impossible to know for sure without any further written evidence. But given that a two-wheeled cart functions perfectly well without a third wheel, it’s clear where the notion of something being proverbially useless or redundant originated here. And from his play in the early 1700s, this image appears to have caught on in the language, and a “third wheel” quickly became a popular go-to metaphor for any ideas, suggestions, or items that appeared completely unnecessary. 

LATE 19TH CENTURY

Finally, in the late 1800s, the expression made the leap from objects to people—in particular, a person accompanying or turning up to a romantic meeting between two other people. This meaning is first recorded in an 1892 story, Beyond the City, by Sherlock Holmes creator Arthur Conan Doyle. 

Since then, the term has remained almost exclusively used throughout the 1900s and 2000s in a similar vein, referring not to an unwanted item, but to an unwanted, unwelcome, or otherwise simply awkward third person who accompanies a courting couple.

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