Ruthful comes from Middle English ruthful, from ruthe ('pity') + -ful, ultimately from Old English hrēow ('sorrow, regret'). The suffix is part of the word's derivational shape, marking the final grammatical or semantic role while the base supplies the central meaning. As an adjective, it denotes "an archaic word meaning full of sorrow or compassion; pitiful", keeping the historical idea close to its dictionary sense. Relevant historical forms include Middle English reuthe and Old English hrēow. Derivative forms include ruthfully, ruthfulness; related words include ruth, rue, ruthless.