This evening our Community will begin chanting the Traditional "O Antiphons" at Vespers. The seven "O Antiphons" (also called the "Greater Antiphons" or "Major Antiphons") are prayers that come from the Breviary's Vespers during the Octave before Christmas Eve, a time which is called the "Golden Nights."
Each Antiphon begins with "O" and addresses Jesus with a unique title which comes from the prophecies of Isaias and Micheas (Micah), and whose initials, when read backwards, form an acrostic for the Latin "Ero Cras" which means "Tomorrow I come." Those titles for Christ are:
Sapientia
Adonai
Radix Jesse
Clavis David
Oriens
Rex Gentium
Emmanuel
Above is this evenings antiphon, click here for an audio clip (from Fisheaters.com)