Just looking at it, the word bizarre is so bizarre that it might not be Indo-European. In English, it's confirmed to be a loanword from French- it traces to bizarre, meaning "odd and fantastic", very similar to today. This is where etymologists get confused. The word has many indications that it could come from Basque and the word bizar, meaning "beard". This supposedly makes sense because there were many odd beards around in twelfth-century Basque Country. Since Basque isn't IE, the word would come from Proto-Basque bisar, which meant something like "hair"> However, this uber-cool theory has been largely refuted, and the current etymology favors the Italian word bizzarro (which had more of a connotation meaning "freaky"). now since many bursts of anger were freaky, this goes to the word bizza, meaning "tantrum". Strange as this is, bizza would go back to the German word biessen, meaning "to bite", and since babies both bite and throw tantrums, the meaning changed. This, through Old German and Proto-Germanic, goes back to the Proto-Indo-European word bheyd, meaning "split", since "bites" "split" stuff. In any case, it may be concluded that the origin of bizarre is truly bizarre.
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.