In James Cook's 1777 book A Voyage to the Pacific Ocean, he detailed the Tongan custom of declaring immoral things taboo. This mainly included menstruation, but also other "unclean" things. There are two possible origins of this. The first is that it's from ta-bu, which meant "sacred" and is a portmanteau of ta, meaning "mark", and bu, meaning "especially" (emphasizing the importance of the mark in question). The more likely theory (since it actually has cognates in other Polynesian languages) is tapu, a word also with a similar definition of "sacred" but able to be reconstructed to a Proto-Polynesian word tapu, "prohibited". Whatever the case, finding out the truth is difficult due to a lack of evidence, but it is nonetheless clear that what is taboo to us is blasphemy to the ancient people of the South Pacific.
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.