The expression coup de grâce (pronounced [ˌkuːdəˈgrɑːs]; French pronunciation: [kudə ɡʁas] “blow of mercy”) means a death blow intended to end the suffering of a wounded creature. The phrase can refer to killing civilians or soldiers, friends or enemies and with or without the consent of the sufferer.
The French pronunciation of the phrase is [ku də gras], but many English speakers mispronounce it as [ku de’gra]. Omitting the final “s” is an example of a hyperforeignism: in French, this mispronunciation sounds like coup de gras, which means “blow of fat”, or cou de gras, which means “neck of fat.”