Silencer is what Maxim called them when he started to market them over 100 years ago. In the UK some people use the words silencer and muffler to denote their use on engines.
Silencer is a legal term in the USA, I do not think the ATF will approve a form 1 or 4 if a person writes in any other word than silencer.
Occasionally someone will tell me that I do not know about silencers because I do not call them suppressors. They are a comical combination of ignorance and arrogance.
Ranb