The quality of being cruel and having no pity or mercy when pursuing a goal, with complete disregard for others' suffering.
From 'ruthless' (from Old English 'hreow' meaning pity/sorrow, with the prefix 'un-' becoming 'rut-'). The '-ness' suffix transforms the adjective into an abstract noun describing the condition or quality.
The word 'ruth' (pity) is almost extinct in modern English except in 'ruthless'—this one word preserves an old Anglo-Saxon emotion that's otherwise vanished from our everyday vocabulary.
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