taboo /təˈbuː/verb 3adjective 2noun 2forms 5 verb3 •To mark as taboo. •To ban or prohibit.They lunched, but if the subject of Carrados had been tabooed the meal would have been a silent one. — 1914 •To avoid. adjective2 •Excluded or forbidden from use, approach or mention.Incest is a taboo subject in most soap operas.Sweets and fats are strictly taboo in my home. •Culturally forbidden. noun2 •An inhibition or ban that results from social custom or emotional aversion.It is true indeed that a taboo - in order to be a proper taboo - must not rest in the general mind on argument or reason. — 1920 •Something which may not be used, approached or mentioned because it is sacred. formstabooed · tabooing · taboos · more taboo · most taboo