One who excepts; a person who makes exceptions or who objects to something.
From Latin 'exceptor,' an agent noun from 'exceptare' (to except). The '-er' suffix in English directly parallels the Latin '-or' to denote an actor of the verb.
Interestingly, this word appears in Shakespeare and legal documents because English legal courts heavily borrowed Latin terminology—an 'excepter' had official standing to file objections.
Complete word intelligence in one call. Free tier — 50 lookups/day.