Search Result for "ruthlessness": 
Wordnet 3.0

NOUN (2)

1. mercilessness characterized by a lack of pity;
[syn: pitilessness, ruthlessness]

2. feelings of extreme heartlessness;
[syn: cruelty, mercilessness, pitilessness, ruthlessness]

The Collaborative International Dictionary of English v.0.48:

Ruthless \Ruth"less\, a. Having no ruth; cruel; pitiless. [1913 Webster] Their rage the hostile bands restrain, All but the ruthless monarch of the main. --Pope. [1913 Webster] -- Ruth"less*ly, adv. -- Ruth"less*ness, n. [1913 Webster]
WordNet (r) 3.0 (2006):

ruthlessness n 1: mercilessness characterized by a lack of pity [syn: pitilessness, ruthlessness] 2: feelings of extreme heartlessness [syn: cruelty, mercilessness, pitilessness, ruthlessness]
Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "ruthlessness": animality, atrociousness, barbarity, barbarousness, beastliness, bestiality, bloodiness, bloodlust, bloodthirst, bloodthirstiness, bloody-mindedness, brutality, brutalness, brutishness, cannibalism, cruelness, cruelty, ferociousness, ferocity, fiendishness, fierceness, flintiness, hardness, harshness, heartlessness, inclemency, inexorableness, inhumaneness, inhumanity, mercilessness, pitilessness, relentlessness, remorselessness, sadism, sadistic cruelty, sanguineousness, savagery, short shrift, tender mercies, truculence, uncompassionateness, unfeelingness, unforgivingness, unmercifulness, unremorsefulness, unsympatheticness, unyieldingness, vandalism, viciousness, violence, wanton cruelty