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.
Phrase this is known as the head-word, or the head. The syntactic category of the head is used to name the category of the phrase; for example, a phrase whose head is a noun is called a noun phrase. The remaining words in a phrase are called the dependents of the head. In the following phrases the head-word, or head, is bolded: The above five examples are the most common of phrase types; but, by the logic of heads and dependents, others can be routinely produced. For instance, the subordinator phrase: By linguistic analysis this is a group of words that