While reading to-day's lessons from Matins (owing to laziness, I am skipping the psalms thereof at present), I noted the phrase aures Domini Sabaoth (the ears of the Lord of hosts),which cropt up in James v, 4 (the first two lessons being a concatenation of James v, 1-16: well worth reading and consideration). There are four Hebrew words - leaving aside proper names of course - that occur in the New Testament and have passed into Christian use, untranslated and merely transliterated, of which Sabaoth is one; the others are Amen, Alleluia (otherwise spelt Hallelujah as the Milanese Rite does, plus some Protestants), and Hosanna.
Our Lord many times - 75 times - in the Gospels prefixes His sacred utterances with the solemn asseveration "Amen, I say unto you" (as in the Synoptics) or with the redoubled "Amen, Amen, I say unto you" (as in St John's account) - more's the pity that modern translations don't leave these Amen's as they are given in the Greek (I think of the Jerusalem Bible version that I hear read at Mass in the vernacular). Since it is indeed Very God, I Am, Who speaks, no wonder that St John in the Apocalypse records Our Jesus being surnamed "the Amen, the witness true and faithful" (Apoc. iii, 14)! It is through Him that we sound the Amen to the glory of God (II Cor. i, 20).
Before the Gospel (except during the austerities of Septuagesimatide, Lent, fasting days and Requiems) - and elsewhere in the chants of the Liturgy during Eastertide, such the overflowing joy of the Church at the Resurrection of Her Master - the Hebrew word Alleluia is sung as a cry of almost inarticulate delight and joy: it stems from the Hebrew phrase that may be simply rendered Hallelu-Yah, "Praise God". In the modern Divine Office, a canticle taken from Apocalypse xix is sung weekly at Vespers: in that passage Alleluia is the word included many times.
Sabaoth and Hosanna are mysterious words; we sing and shout them in the Sanctus prefacing the consecration of the Sacrament at Mass, joining in with the ceaseless Divine praise sung by the heavenly hosts: "the heavens are telling the glory of God..." - and since the Church is one, all His worshippers unite to magnify His Name, the Name of the Lord God of Hosts, Whose Son, the Blessed One Who came in His Name, and now comes again in the Eucharist, was once hymned with Hosannas ere He was crucified for us sinners and our salvation, and so rightly is lauded with the same words because His saving Sacrifice is made present hic et nunc upon the altar.
In the New Testament, the word Sabaoth occurs twice: once, quoting Isaias, in Romans ix, 29; and again in James v, 4. The Hebrew seems to signify God as the Lord of starry hosts. Hosanna - the cry of the crowds and children on Palm Sunday (St Matthew xxi, St Mark xi, St John xii) - meant originally "Give victory now", but had by Our Lord's time become a stereotyped cry - a cry of victory: the Greeks call the Sanctus the Hymn of Victory (epinikion hymnon).