/ təˈbuː; NAmE / noun ( pl. ta·boos ) taboo (against / on sth)
1.
a cultural or religious custom that does not allow people to do, use or talk about a particular thing as people find it offensive or embarrassing :
an incest taboo
a taboo on working on a Sunday
to break / violate a taboo
Death is one of the great taboos in our culture.
2.
a general agreement not to do sth or talk about sth :
The subject is still a taboo in our family.
► taboo adjective :
in the days when sex was a taboo subject
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WORD ORIGIN
late 18th cent.: from Tongan tabu set apart, forbidden; introduced into English by Captain Cook.