From Longman Dictionary of Contemporary Englishmercymer‧cy /ˈmɜːsi $ ˈmɜːrsi/ ●●○ noun 1 [uncountable]KIND if someone shows mercy, they choose to forgive or to be kind to someone who they have the power to hurt or punish He showed no mercy to his enemies. God have mercy on his soul.beg/cry/plead for mercy The boy was screaming and begging for mercy.2 → at the mercy of somebody/something3 → mercy flight/mission etc4 → leave somebody to somebody’s (tender) mercies5 → throw yourself on somebody’s mercy6 → it’s a mercy (that) → be thankful/grateful for small mercies at small1(13)COLLOCATIONSphraseshave mercy (on somebody) (=act in a kind or forgiving way - often used to express a hope or prayer)‘God have mercy on me!’ Miss Barton cried.show mercy (to somebody) (=act in a kind or forgiving way)He showed no mercy to those who had angered him.ask for mercyThe only thing I can do now is ask for mercy.beg/plead for mercy (=ask in a desperate way for someone's mercy)She continued the punishment, although they begged for mercy.scream/cry for mercyHe screamed for mercy, shouting 'don't shoot!'.adjectivesgreat mercyGod in his great mercy has forgiven you.God's mercyWill we still receive God's mercy if we refuse to repent?divine mercy (=the mercy of God)He did not lose his faith in God and divine mercy.infinite mercy (=the quality of mercy that God has, which never ends)He expressed his thanks for the infinite mercy of God in helping him escape from his own sinful life.
Examples from the Corpus
mercy• Mercy, mercy, mercy, he croaked, his first surrender to fatalism.• Priest: Lord, have mercy.• This man had no mercy on the people he killed.• It is not that they showed no mercy on the streets of Jericho.• We are at the mercy of our own detachment.• Even compassion for a man so much at the mercy of his physical urges.• With monarchy, the essential problem is that power is put at the mercy of relatives and genetics.beg/cry/plead for mercy• Their screams of horror and cries for mercy only brought a smile to my face.• In self-defense Jack calls on his stick, which beats the father until he cries for mercy.• Could make him cry for mercy.• The elder brother was shot in the stomach as he knelt pleading for mercy.• The killer was not hit but lay pleading for mercy.• Mad faces pushed against the grilles in the doors, tortured ones begging for mercy.• They cried for mercy but their pleas were met with abuse and laughter.• The class have to plead for mercy on his behalf, but the King's envoy will only accept written pleas.Origin mercy (1100-1200) Old French merci, from Latin merces “price paid, payment for work”, from merx “things for sale” 