monstrous in WordNet English dictionary

1. shockingly brutal or cruel
   "murder is an atrocious crime"; "a grievous offense against morality"; "a grievous crime"; "no excess was too monstrous for them to commit"
   atrocious  flagitious  grievous  monstrous 
   
2. distorted and unnatural in shape or size; abnormal and hideous
   "tales of grotesque serpents eight fathoms long that churned the seas"; "twisted into monstrous shapes"
   grotesque  monstrous 
   
3. abnormally large
   monstrous