It almost feels like the words prequel and sequel were coined at the same time. Likewise, it seems like prequel has been around as a word forever. Both of these are incorrect misconceptions; prequel was actually coined in 1973 and patterned off the pre-existing word sequel, which had been around since the 1400s. It's mind-boggling to me that we didn't have a word for it before then. Sequel derives from Middle French sequelle, from Latin sequella, from the verb sequor, meaning "to follow". This, through Proto-Italic sekwor, can be reconstructed as coming from the Proto-Indo-European root sek, also "to follow". So se- was never a prefix, but part of the word, and the insertion of pre- mistakenly assumed that it was one. Pre- comes from Latin prae, "before", which is from Proto-Indo-European preh, meaning "before". So a prequel is "before following". Sequel is still used a lot more, but only because there are more prequels out there. It only took a few years for prequel to catch on as a normal word.
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