Cyclopedia of Biblical, Theological and Ecclesiastical Literature
[many Ome'ga, but against the proper rule] (ω . fully Ω μέγα, i.e. the great or long o, in distinction from. ῎Ομικρον, the short o), the last letter of the Greek alphabet, as Alpha is the first. It is used metaphorically to denote the end of anythiing: "I am Alpha and Omega, the beginning and the ending... the first and the last" (Revelation 1:8; Revelation 1:11; comp. Revelation 21:6; Revelation 22:13). This may be compared with Isaiah 41:4; Isaiah 44:6, "I am the first and I am the last, and beside me there is no God." So Prudentius (Cathemer. hymn. 9:11) explains it:
"Alpha et O cognominatur: ipse fons et clausula
Omninum quse sunt, fuerunt, quneqne post futura sunt."
(See ALPHA). The symbol את, which contains the first and last letters of the Hebrew alphabet, is according to Buxtorf (Lex. Talm. p. 244), "‘ among the Cabalists often put mystically for the beginning and end, like A and ? in the Apocalypse." Schoettgen (Hor. Hebr. 1:1086) quotes from Jalkut Rubeni (fol. 17, 4), "Adam transgressed the whole law from א to ת ," that is, from the beginning to the end. It is not necessary to inquire whether in the latter usage the meaning is so full as in the Revelation: that must be determined by separate considerations. As an illustration merely, the reference is valuable. Both Greeks and Hebrews employed the letters of the alphabet as numerals. It the early times of the Christian Church the letters Α and Ω were combined with the cross or with the monogram of Christ (Maitland, Church in the Catacombs, p. 166-8). (See MONOGRAM OF CHRIST).
These files are public domain.
McClintock, John. Strong, James. Entry for 'Omega'. Cyclopedia of Biblical, Theological and Ecclesiastical Literature. https://www.studylight.org/encyclopedias/eng/tce/o/omega.html. Harper & Brothers. New York. 1870.