You have probably seen the letters "R.I.P." on gravestones or spooky Halloween decorations. The abbreviation stands for the Latin phrase requiescat in pace, which in English means "rest in peace."
You may also see or hear the phrase requiescat in pace at funerals, in obituaries, or on memorials to those who have died. It is used as a prayer or wish for the soul of the departed to have serenity in the afterlife. In Edgar Allan Poe's classic short story "The Cask of Amontillado," the narrator uses the phrase, but flipped — "In pace requiescat!" — at the end, after walling his rival up alive.