Taboo is an English borrowing from Tongan tabu. A word for prohibition became available for many kinds of social restriction in English. The spelling changed slightly as its range of use expanded.
taboo
A prohibition, or something forbidden.
Taboo came from Tongan.
How taboo reached English
oldest firstTongan
tabu
‘Forbidden’
into English
English
taboo
‘A prohibition’
The story of taboo
Related
A word can move from a particular cultural setting into broad everyday use.