I learned a fun fact from my Princeton college interviewer today! Apparently facetious is one of only two words in the English language to have all the vowels in alphabetical order (the other being abstemious, and, as a bonus, both can take the -ly suffix to fit the "sometimes y" rule). This beautiful word for "unserious" (often at inopportune occasions) came from French facetieux in the 1590s, the root being facetie, or "joke". This in turn derives from the Latin adjective facetus, which could mean anything from "witty" to "elegant", but mostly similar to the modern definition. Where that comes from is actually a bit of a mystery. The going theory is that it's somehow related to the Latin word for "torch", facis, through the Proto-Indo-European reconstruction gehk, "to shine", but that's really sort of a stretch.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd