to prevent someone from discussing something in public. This is often achieved through a gagging order, an official instruction not to discuss eg information relating to a legal case or other official matter in public
Mr Hemming said he wanted a promise that the family would not be gagged if legal action was taken.
to put a piece of cloth (=a gag) over someone's mouth stop them from speaking or screaming etc
The victims had all been bound and gagged with items of their own clothing.