The story
First word of the Latin phrase requiēscat in pāce (“may he/she rest in peace”). The Latin word requiēscat means "may he/she rest" and is a form of the Latin verb requiēscō (“to rest, repose”).
Etymology from Wiktionary, CC BY-SA 4.0.
requiescat
Today it means: A prayer for the peaceful repose of the soul of a dead person Full definition →