There are many alterations and possible origins of the word voodoo. The word voodoo that we know and associate with religious witchcraft only describes the religion in Louisiana. In Haiti, it's spelled vodou, in Brazil it's spelled vodum, in Africa it's spelled vodun, and in other parts of the Caribbean it's written vodu. All these words describe spiritual religions, but they differ by practice as well as spelling. Of these five variations, voodoo is by far the most used in English, but in other languages like French (which Haiti speaks) vodou is more used, and in Spanish the margins are a lot closer. All these Caribbean variations were brought over from Africa with the slave trade, and originate in the aforementioned term vodu, which once meant something more like "spirit" (since the voodoo religion espouses spiritual possessions). African words are always hard to trace because of the lack of written records and etymological interest, but this may be from a local word vo, meaning "harmful". Cognates have been suggested from Semitic to Italic languages. Whatever the case, it's part of the Niger-Congo language family for sure. VOODOO!
Adam Aleksic, a leading contender for valedictorian of his high school, is a 208-month-old boy with disturbing interests in etymology, vexillology, geography, and law. Adam would like to one day visit Tajikistan and just won an essay contest on linguistics!
The Etymology Nerd