WordNet sense 1 (marked by extreme and violent energy):

ferocious, furious, savage

WordNet sense 2 (acting with or marked by or resulting from great force or energy or emotional intensity):

violent

WordNet sense 3 (marked by extreme intensity of emotions or convictions; inclined to react violently; fervid):

trigger-happy, vehement, tearing

WordNet sense 4 (in an extreme degree):

intense

WordNet sense 5 (ruthless in competition):

cutthroat, bowelless

WordNet sense 6 (having or showing no mercy):

unmerciful

WordNet sense 7 (violently agitated and turbulent):

boisterous, rough

WordNet sense 8 ((especially of weather) affected or characterized by storms or commotion):

stormy