Pegasus is quite a prolific word. It's been the name of a type of fish since 1842, it's been used in heraldry to refer to winged horses since 1542, the first reference of a constellation being named Pegasus was in 1449, and for many eons before that the word's been associated with the Pegasus - the figure from Greek mythology, the original winged horse who was the child of Poseidon and Medusa. This word, taken from Ancient Greek Pegasos by way of Latin, has a surprisingly obscure etymology. It's thought that it could come from the noun pege, meaning "spring" (and this would make sense because Pegasus was born near a spring in the stories), which would be from a Pre-Greek source. However, that's uncertain, and nobody really knows for sure: it could also be from the Luwan word pihassas, meaning "lightning" (which would check out because Pegasus was Zeus' bearer of lightning bolts) and coming from Hittite. That's also hotly disputed, though; it's unlikely we'll find out for sure.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.