When someone says "not hear of it," it means that they refuse to listen to or consider a particular suggestion or idea. There are several synonyms for this phrase, which can be used interchangeably depending on the context and the situation. Some of the most common synonyms for "not hear of it" include "reject," "refuse," "decline," "object," "disapprove," and "protest." All of these words convey a similar meaning and indicate a clear unwillingness to entertain the possibility of a particular action or proposal. Other possible alternatives might include "dismiss," "ignore," "veto," or "shoot down," depending on the tone and formality of the conversation.