Oremus

Oremus (Latin: "Let us pray") is the invitation to pray, said before short prayers in the Catholic Mass the Anglican and Episcopalian Holy Eucharist and Divine Offices, and the Lutheran Divine Service, as well as other Western Christian liturgies.

It is used as a single exclamation in the East (in the rites of the Assyrian and Syriac Orthodox churches), denoting the imperative "Pray" or "Stand for prayer" (in the Coptic Church); most commonly, however with a further determination, "Let us pray to the Lord" (τοῦ Κυρίου δεηθῶμεν, used throughout the Byzantine Rite, where the laity replies with Kyrie Eleison before the priest recites the prayer), and so on. Louis Duchesne thought that the Gallican Collects were also introduced by the word "Oremus" ("Origines du Culte", Paris, 1898, 103). That was not the case in the Mozarabic Rite, where the celebrant uses the word only twice, before the Agios and Pater noster.