1. bloodthirsty, ferocious, merciless, relentless. Cruel, pitiless, ruthless, brutal, savage imply readiness to cause pain to others. Cruel implies willingness to cause pain, and indifference to suffering: a cruel stepfather. Pitiless adds the idea of refusal to show compassion: pitiless to captives. Ruthless implies cruelty and unscrupulousness, letting nothing stand in one's way: ruthless greed. Brutal implies cruelty that takes the form of physical violence: a brutal master. Savage suggests fierceness and brutality: savage battles.