The word flatulence didn't always carry such a noxious connotation. It was coined in 1711, but not really, since it's a direct loanword from French flatulence. This is from the Middle French word flatulent (from which we got ours; it's much older than the former), which meant (as today) "affected with gas". This is from the modern Latin word flatulentus, a variation of flatus, a jack-of-all-trades word dealing with air, including definitions such as "blow", "breathe", and "snort". Not necessarily smelly, I might emphasize. One theory traces this to an earlier word, flo, meaning "to breathe or blow". This would be (through Proto-Italic flao) from the reconstructed Proto-Indo-European root bleh, or "to blow". This possibly has connections to another Proto-Indo-European word, bhel, which meant "to swell" and connected to all this since you swell up before blowing out air. What we can see here on a grander picture is that one type of air release became another over time. Fun fact: the word flatulence had a 300% higher usage during 1867 than it does today; it's losing popularity both to euphemisms like passing gas and cruder words like fart, both of which have increased in usage since then.
Adam Aleksic, a leading contender for valedictorian of his high school, is a 208-month-old boy with disturbing interests in etymology, vexillology, geography, and law. Adam would like to one day visit Tajikistan and just won an essay contest on linguistics!
The Etymology Nerd