no-no
Longman Dictionary of Contemporary English 5++LDOCE 5++ˈno-no noun [singular] informal NOT DO somethingsomething that you must not do because it is considered to be unacceptable behaviour 不准干的事；不能接受的事 Colouring your hair was a no-no at that time. 染发在那时是绝不允许的。
Examples from the Corpus
no-no• Earrings and heavy chains around the neck are a no-no on the field.• Handwritten signs in the restaurant are a no-no.• The use of fresh ground beef is a no-no.• Apparently, this is a no-no in insurance land.• In technical terms, this is a big no-no.• And crying for me was a big no-no in business life.• A word of warning, though-counters are generally considered a design no-no.• There is lots of touching, and I think touching, in our society, is a real no-no.ˈno-no nounChineseSyllable
you something do not because that must Corpus
no-no
ˈno-no
noun [singular] informal
something that you must not do because it is considered to be unacceptable behaviour:
Colouring your hair was a no-no at that time.
ˈno-no
noun [singular] informalsomething that you must not do because it is considered to be unacceptable behaviour: