Q: What is the origin of the phrase “double-jointed”? And how did its usage get to be so widespread when the word “flexible” suffices?
A: The phrase “double-jointed,” meaning “having joints that permit a much greater degree of movement of parts of the body than is normal,” dates back to the early 19th century, according to the Oxford English Dictionary.
The first published reference in the OED (at least in the anatomical sense) dates from 1831, when the phrase appeared in John Roby’s Traditions of Lancashire, a study of English folklore.
In one of the tales cited, a character says of another: “The knave is shrewd and playful, but of an incredible strength, being, as ye may observe, double-jointed.”
The expression apparently found early favor in the medical community. A variation on the theme appeared in 1912 in the British medical journal The Lancet, in an article describing a boy with “double-jointedness.”
“The joints were very loose,” the article said, “and the child took particular pleasure in forming almost circles by locking the index and middle finger of each hand.”
Nowadays, however, physicians prefer the terms “hypermobility” or “hyperlaxity” to “double-jointedness.”
In fact, the adjective “double-jointed” and the noun “double-jointedness” are misnomers; people with the condition don’t have any more joints than people without it.
Why has “double-jointed” proved so popular with the public? Perhaps because it’s more evocative than “flexible” – or “hypermobile” or “hyperlax.” Misnomer or not, it’s still very much with us.