Rest in peace (acronym R.I.P.) in the second person singular, or “Requiescite in pace” in the second person plural. In the common phrase "Requiescat in pace" the "-at" ending is appropriate because the verb is a third-person singular present active subjunctive used in a hortative sense: "May he/she rest in peace." The phrase was first found on tombstones some time before the fifth century. It became ubiquitous on the tombs of Christians in the 18th century, and for High Church Anglicans, Methodists, as well as Roman Catholics in particular, it was a prayerful request that their soul should find peace in the afterlife.
Latin Wikipedia When occasionally a term for a modern concept cannot be found, the customary practice is to do exactly what most other languages do: to borrow an international word (often from a Romance language or English). Such direct borrowing was done for the particle names and and for the unit of temperature . The word is given a Latin morphology if this can be done easily, or, if not, used unchanged in its foreign form; but many international words already have a Latin or Graeco-Latin appearance, because Greek and Latin have always served as sources of new scientific terminology. Vicipaedia made