On the first day of Christmas my true love sent to me
A partridge in a pear tree.
Perhaps it’s the cynic in me that brings immediately to mind the question “why” and the scientist that asks “how.” But the etymologist is much more fascinated by the flatulent origins of the word. Yes, you heard right – flatulent or “related to farts.”
The word was borrowed from the French perdriz, which is found in Anglo-Norman with varieties such as perdix, pardis , pardriz , partriz , and partreiz. This in turn can be traced back to the Latin perdix and even further to the Greek perthiks (πέρδικ), which is thought to refer more specifically to the Rock partridge (Alectoris graeca) that’s found in Greece and southern Europe in general.
The Oxford English Dictionary then goes on to suggest that perthiks is actually derived from the Greek perthesthai (πέρδεσθαι), which means “to break wind.” Apparently the connotation here is “perhaps after the noise made by the bird as it flies away.” At this point, I should say that I have no experience whatsoever of the noise a partridge might make when it takes flight but if only for the sake of a good story I’m willing to believe the folks at the OED, who, for all I know, may have sent out hundreds of field agents to listen to farting partridges to check the veracity of the claim.
And why “in a pear tree” as opposed to any other? Do partridges like pears in particular? And where do you find pears on trees at Christmas? Well, one reasonably plausible (at the phonetic level) explanation that was recently alluded to by the good folks at Mental Floss magazine is that the original line was “A partridge, une perdrix” where the English and French words were used. Those of you familiar with French can hear that the pronunciation of “in a pear tree” and “une perdrix” are stunningly similar. Given that non-French speakers – and singers – are likely to “hear” an English phrase (“a pear tree”) than a French one, “a partridge in a pear tree” sounds pretty good.
So next time you are tempted to be witty and sing the line, “and a fartdridge in a pear tree,” you can bask in the knowledge that you’re actually correct!
 This mishearing of words, especially from a foreign language, gives rise to what are called mondegreens, coined in 1954 by poet Sylvia Wright who wrote that for many year she had thought the line “They hae slain the Earl o’ Moray, And laid him on the Green” as “They hae slain the Earl o’ Moray and Lady Mondegreen.” Several websites are available that list some classics; here are just two to start you off: Mondegreens and Misheard Lyrics.