or tabu Taboo

Taboo, or tabu, prohibition linked to an object, place, or person by law or social custom. The word taboo comes from the Polynesian word tapu, meaning something sacred, dangerous, or unclean. In Polynesia, violation of a taboo requires a ritual purification and at times may even warrant the death of the offender (to save the community from suffering ill consequences). In most western societies incest is considered taboo. This taboo was established hundreds of years ago to promote genetic and cultural exchanges between members of clans and tribes by prohibiting the intermarriage of close family relations.