Real Dictionary

mercy
Mercy is used to describe a special journey to help someone in great need, such as people who are sick or made homeless by war.
uncountable noun: If someone in authority shows mercy, they choose not to harm someone they have power over, or they forgive someone they have the right to punish.

mercy in American English
a refraining from harming or punishing offenders, enemies, persons in one's power, etc.; kindness in excess of what may be expected or demanded by fairness; forbearance and compassion
noun: a female given name
noun: compassionate or kindly forbearance shown toward an offender, an enemy, or other person in one's power; compassion, pity, or benevolence

mercy in British English
noun: compassionate treatment of or attitude towards an offender, adversary, etc, who is in one's power or care; clemency; pity