Whence came that foul stench?
Just kidding, that isn’t the type of origin we’re going to sniff out today. Let’s take a look at where the word “fart” came from.
By the minimal research that I did in order to write this post, it appears that “fart” is a word as old as the wind, or rather, the breaking of that wind. Our modern spelling has its roots in the Old English word “feortan,” but it dates back much earlier than that, possibly from around 5,500 years ago.
The fascinating thing about the word “fart” is that it is as widespread as the thing that it represents. Its cognates (words derived from the same root word but representative of the local speaking group) can be found in all corners of the globe (Old High German ferzan, Old Norse freta, Danish fjerte, Sanskrit pard, Greek perdein, Lithuanian perdzu, Russian perdet, source).
The quick and dirty answer to this word’s origin is that it is imitative of the sound that it makes. It is onomatopoeic (which paradoxically means nothing like how is sounds). You can’t say “fart” without it sounding a bit like one.
And if you think that my explanation stinks, there’s a much better article that says the same sort of thing (but in a smarter way) over here.
On an almost-unrelated note, the partridge (a bird in the pheasant family popularized by Christmas tunes with pear trees and 70’s television family bands) gets its name from the same ancient root word due to the sound they make when flushed (bathroom-related pun not intended) from their hiding places.