A person who receives mercy is hurt or punished less than what was originally expected or deserved. Mercy is shown to people who are guilty of bad behavior, but mercy may also be shown to people who are completely innocent of any wrongdoing.
The judge showed no mercy on the man who was guilty of theft.
The lion showed mercy on the mouse that he captured; he let the mouse go.
The captured soldiers begged for mercy before they were executed.
The man asked God for mercy as his house collapsed in the storm.
The family of the young man begged for mercy.
The word "merciful" is an adjective:
The merciful lion allowed the mouse to go free.
A merciful judge reduced the man’s prison sentence from ten years to two.
The opposing team was unmerciful, beating their opponents with a score of 20 to nothing. (The word "unmerciful" is the opposite of "merciful.")