taboo

adjective
1
considered so offensive or embarrassing that people must not mention it
تابو, ممنوع, ناگفتنی
noun
1
a cultural or religious custom that does not allow people to do, use or talk about a particular thing
تابو, حرام, ممنوع, قدغن
2
a general agreement not to do something or talk about something
تابو, ناپسند, تحریم اجتماعی
The subject is still a taboo in our family.