2899: Folk Etymologies: An Arm and a Leg Nov 28, 2024

 The phrase “to cost an arm and a leg” (or conversely to charge etc.) is, like many idioms, difficult to track down. The obvious meaning is that it is expensive in that no one would be quick to remove them for any reason. There is another explanation offered commonly, which is that in the world of portraits, a bust was the cheapest, and the larger amount of one’s body was included in the painting, the more it cost, i.e. one was being charged literally per arm and leg. Again, it is usually very difficult to prove where a phrase comes from compared to the etymology of a single word, but a good way to prove something isn’t the origin, and is instead folk etymology, is with dating. 

Oxford English only first records this phrase in the USA in the mid-20th century, and would not have been born out of the era of portraiture. Other explanations, like 18th century British coinage or Roman culture etc.—all of which have been conjectured—are almost certainly wrong, but are more compelling stories than the plain meaning given at the start: they are precious to a person.

Indeed, similar phrases have been seen throughout history. The Biblical line, “if I would forget you, Jerusalem, let my right hand forget [itself]” paints a similar picture of value being compared to the utility of a hand. 

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