clemency vs mercifulness

clemency and mercifulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
clemency	Yes	No	No	No
mercifulness	Yes	No	No	No

As nouns, clemency and mercifulness are synonyms defined as:

clemency and mercifulness: leniency and compassion shown toward offenders by a person or agency charged with administering justice

Other synonyms of clemency include mercy.

clemency (noun)	mercifulness (noun)
leniency and compassion shown toward offenders by a person or agency charged with administering justice	leniency and compassion shown toward offenders by a person or agency charged with administering justice
good weather with comfortable temperatures	a disposition to be kind and forgiving
	the feeling that motivates compassion