The Collaborative International Dictionary of English v.0.48:

omega \o*me"ga\ ([=o]*m[=e]"g[.a] or [=o]*m[=a]"g[.a] or
   [=o]"m[-e]*g[.a]; 277), n. [NL., fr. Gr. 'w^ me`ga, i.e., the
   great or long o. Cf. Mickle.]
   1. The last letter of the Greek alphabet. See Alpha.
      [1913 Webster]

   2. The last; the end; hence, death.
      [1913 Webster]

            "Omega! thou art Lord," they said.    --Tennyson.
      [1913 Webster]

   Alpha and Omega, the beginning and the ending; hence, the
      chief, the whole. --Rev. i. 8.
      [1913 Webster]

            The alpha and omega of science.       --Sir J.
                                                  Herschel.
      [1913 Webster]

WordNet (r) 3.0 (2006):

omega
    n 1: the ending of a series or sequence; "the Alpha and the
         Omega, the first and the last, the beginning and the end"--
         Revelation [syn: omega, Z]
    2: the last (24th) letter of the Greek alphabet

The Free On-line Dictionary of Computing (19 January 2023):

Omega

   1.  A prototype-based object-oriented
   language from Austria.

   ["Type-Safe Object-Oriented Programming with Prototypes - The
   Concept of Omega", G. Blaschek, Structured Programming
   12:217-225, 1991].

   2.  A successor to TeX extended to handle the
   Unicode character set.

   (http://ens.fr/omega/).

   (1997-11-20)