The word "most silencing" refers to something that completely suppresses or quiets a sound or voice. Some synonyms for the word "most silencing" include "muffling," "muzzling," "suppressing," "damping," "stifling," "quieting," "hushing," "abating," "deadening," and "pacifying." These words can be used in various contexts, such as in describing an object that absorbs sound, a person who subdues a loud argument or protest, or a situation where an authoritative figure suppresses freedom of speech. The choice of synonym depends on the tone and nuance the writer wants to express in their writing or speech.