Versions of this advent hymn have been sung for a long time. The Latin text, “Veni Emmanuel,” comes from the 12th century; the plainsong tune can be traced to a 15th century Franciscan processional, but the roots of the melody may go back as far as 8th century Gregorian chant.

Immanuel or Emmanuel? The Hebrew name עִמָּנוּ אֵל (Isaiah 7:14) is usually transliterated from Hebrew into English as Immanuel. It was transliterated from Hebrew into Greek as Ἐμμανουήλ (Matthew 1:23), which was then transliterated from Greek into English as Emmanuel. Transliteration is the process of trying to spell in your own alphabet a word previously written in a different alphabet; the extra step of transliterating via Greek resulted in an alternate English spelling, but there is no difference in meaning, which is “God is with us” in both versions.

Notice, in the stanzas below, that the meaning of the text doesn’t necessarily pause at the end of a line. This is especially notable in the first stanza, which needs to be sung and heard as a single sentence.

1. O come, O come, Emmanuel,
And ransom captive Israel
That mourns in lonely exile here
Until the Son of God appear.  

Refrain: Rejoice! Rejoice! Emmanuel shall come to you, O Israel.

2. O come, Thou Dayspring, come and cheer
Our spirits by thine advent here.
Disperse the gloomy clouds of night,
And death’s dark shadows put to flight. Refrain

3. O come, Thou Rod of Jesse, free
Thine own from Satan’s tyranny.
From depths of hell thy people save,
And give them victory o’er the grave. Refrain

4. O come, Thou Wisdom from on high,
And order all things far and nigh.
To us the path of knowledge show,
And cause us in her ways to go. Refrain

5. O come, Desire of nations: bind
All peoples in one heart and mind.
Bid envy, strife, and discord cease;
Fill the whole world with heaven’s peace. Refrain

This is a nice rendition by Barlow Girl; they have not included all the stanzas, but they do sing the less-well-known third stanza.

https://www.youtube.com/watch?v=zzW_PmW-LzE