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.”  ~ Fisheaters

17 Dec. O Sapientia – Wisdom

O Sapientia, quae ex ore Altissimi prodidisti, attingens a fine usque ad finem, fortiter suaviter disponensque omnia: veni ad docendum nos viam prudentiae.

O Wisdom, who came from the mouth of the Most High, reaching from end to end and ordering all things mightily and sweetly: come, and teach us the way of prudence.

18 Dec. O Adonai – Lord

O Adonai, et Dux domus Israel, qui Moysi in igne flammae rubi apparuisti, et ei in Sina legem dedisti: veni ad redimendum nos in brachio extento..

O Lord and Ruler the house of Israel, who appeared to Moses in the flame of the burning bush and gave him the law on Sinai: come, and redeem us with outstretched arms.

19 Dec. O Radix Jesse – Root

O Radix Jesse, qui stas in signum populorum, super quem continebunt reges os suum, quem gentes deprecabuntur: veni ad liberandum nos, iam noli tardare.

O Root of Jesse, that stands for an ensign of the people, before whom the kings keep silence and unto whom the Gentiles shall make supplication: come, to deliver us, and tarry not.

20 Dec. O Clavis David – Key

O clavis David, et sceptrum domus Israel: qui aperis, et nemo claudit; claudis, et nemo aperit: veni, et educ vinctum de domo carceris, sedentem in tenebris.

O Key of David, and scepter of the house of Israel, who opens and no man shuts, who shuts and no man opens: come, and lead forth the captive who sits in the shadows from his prison.

21 Dec. O Oriens – Dawn

O Oriens, splendor lucis aeternae, et sol iustitiae: veni, et illumina sedentes in tenebris et umbra mortis.

O dawn of the east, brightness of light eternal, and sun of justice: come, and enlighten those who sit in darkness and in the shadow of death.

22 Dec. O Rex Gentium – King

O Rex gentium, et desideratus earum, lapisque angularis, qui facis utraque unum: veni, et salva hominem, quem de limo formasti.

O King of the gentiles and their desired One, the cornerstone that makes both one: come, and deliver man, whom you formed out of the dust of the earth.

23 Dec. O Emmanuel – Emmanuel

O Emmanuel, Rex et legifer noster, exspectatio gentium, et Salvator earum: veni ad salvandum nos Domine Deus noster.

O Emmanuel, God with us, our King and lawgiver, the expected of the nations and their Savior: come to save us, O Lord our God.

Ero Cras

Take the first letters of each of the titles, starting with the last and working back to the first. You spell: EROCRAS or “ero cras… I will be (there) tomorrow”.

Resources:

• O Antiphons – Fish Eaters
• O Antiphons Prayer Companion – Family Feast and Feria
• O Antiphon Coloring Pages & Prayer Printables – Michele Quigley
• O Antiphon Printable Symbols – Sanctus Simplicitus
• O Antiphon Coloring Pages – O Night Divine
• O Anitphon Wreath – Under Her Starry Mantel
• O Antiphon Craft – Waltzing Matilda
• O Anitphon Craft Ideas – Catholic Icing

O Antiphons Playlist

• O Sapientia – Dec 17
• O Adonai Dec 18
• O Radix Jesse – Dec 19
• O Clavis David – Dec 20
• O Oriens – Dec 21
• O Rex Gentium – Dec 22
• O Emmanuel – Dec 23