In 1908, a snack manufacturing company named Sunshine Biscuits released a crème-filled sandwich cookie called the Hydrox, to decent reception. Four years later, Nabisco came out with their own version of the treat, which they called the Oreo Biscuit. Originally, this had lackluster sales, but it soon took off and reached such immense popularity that people mistook Hydrox for being an off-brand version of Oreo and it died out. In 1921, Nabisco renamed their product to Oreo Sandwich, and they struck again in 1948 with Oreo Creme Sandwich and 1974 with Oreo Chocolate Sandwich Cookie, which is the full name that exists today (although people obviously shorten it to just Oreo, which is evident if you look at the exponential increase of usage of the word since the 1960s). As for the name itself, Nabisco never provided an official etymology but there's a theory that the snack could be named for the oreodaphne genus of the laurel family - a lot of other Nabisco products are also named after plant - or that it was just made to be short and easy to pronounce.
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.