Source : WordNet®

OK
     n 1: a state in south central United States [syn: {Oklahoma}, {Sooner
          State}]
     2: an endorsement; "they gave us the O.K. to go ahead" [syn: {O.K.},
         {okay}, {okey}, {okeh}]
     adv : sentence-initial expression of agreement [syn: {very well},
           {fine}, {alright}, {all right}]