unmercyEtymologyFrom Middle English onmerci, unmerci, unmercy; equivalent to un- (“lack or absence of”) + mercy.unmercy means the lack or absence of mercy; mercilessness. Lexicurio rates it Sui generis — a strength score of 87 out of 100.nounThe lack or absence of mercy; mercilessness.“There is justice and injustice, mercy and unmercy, love and unlove, self and unself, faithfulness and unfaithfulness, the well-being of others and the ill-being of others, the honor of God and the dishonor of God.”