Source : WordNet®

holler
     n 1: a very loud utterance (like the sound of an animal); "his
          bellow filled the hallway" [syn: {bellow}, {bellowing},
          {holla}, {hollering}, {hollo}, {holloa}, {roar}, {roaring},
           {yowl}]
     2: a small valley between mountains; "he built himself a cabin
        in a hollow high up in the Appalachians" [syn: {hollow}]

holler
     v 1: shout out; "He hollered out to surrender our weapons" [syn:
          {holler out}]
     2: utter a sudden loud cry; "she cried with pain when the
        doctor inserted the needle"; "I yelled to her from the
        window but she couldn't hear me" [syn: {shout}, {shout out},
         {cry}, {call}, {yell}, {scream}, {hollo}, {squall}]
     3: complain; "What was he hollering about?" [syn: {gripe}, {grouse},
         {crab}, {beef}, {squawk}, {bellyache}]