ruthless (adj) - showing no mercy, pity, or compassion [rooth-lis]
BACKGROUND: The Old English word ruth, derived from Old Norse, meant sorrow, pity, or compassion. This word also appears in English as rue, meaning regret or sorrow, as in rueful.
“A materialistic person is ruthless with other people but kind to himself. A spiritual person is ruthless with himself but kind to everybody else.” —Jaggi Vasudev
[Our Wednesday Wildcards are fascinating and important words that are not necessarily derived from classical roots.]