con·ven·tion·al·ist \-nələ̇st, -nəl-\noun (-s) 1.: a member or supporter of a convention (as a constitutional convention) 2.: an observer of conventions : a conventional person 3.: an adherent of philosophical conventionalism • con·ven·tion·al·ist·ic\kən|venchənəl|istik, -chnə|li-\adjective