Source : Webster's Revised Unabridged Dictionary (1913)

Presidential \Pres`i*den"tial\, a.
   1. Presiding or watching over. ``Presidential angels.''
      --Glanvill.

   2. Of or pertaining to a president; as, the presidential
      chair; a presidential election.

Source : WordNet®

presidential
     adj 1: relating to a president or presidency; "presidential aides";
            "presidential veto"
     2: befitting a president; "criticized the candidate for not
        looking presidential" [ant: {unpresidential}]