The word bikini has surprisingly radioactive origins. The English word came from French, since the French invented the bikini, and the French word came from an English name for a Pacific atoll that was the site of several nuclear tests. this is kind of a joke: the bikini was where the US "split the atom", and an atome was a single-piece French bathing suit. Anyway, the bikini part of bikini atoll came from the Marshallese appellation pikini. This is likely a combination of pik, meaning "surface" and ni, meaning "coconut". Further research on this is hard to find, because etymologists favor Indo-European languages over supposedly insignificant native tongues, but this probably came from the Proto-Micronesian language, which in turn comes from Proto-Austronesian. Funnily enough, the bi- part of bikini was later on mistaken for a prefix, and caused the creations of the words monokini and trikini.
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