Source : Webster's Revised Unabridged Dictionary (1913)

Omen \O"men\, n. [L. omen, the original form being osmen,
   according to Varro.]
   An occurrence supposed to portend, or show the character of,
   some future event; any indication or action regarded as a
   foreshowing; a foreboding; a presage; an augury.

         Bid go with evil omen, and the brand Of infamy upon my
         name.                                    --Milton.

Omen \O"men\, v. t. [imp. & p. p. {Omened}; p. pr. & vb. n.
   {Omening}.]
   To divine or to foreshow by signs or portents; to have omens
   or premonitions regarding; to predict; to augur; as, to omen
   ill of an enterprise.

         The yet unknown verdict, of which, however, all omened
         the tragical contents.                   --Sir W.
                                                  Scott.

Source : WordNet®

omen
     n : a sign of something about to happen; "he looked for an omen
         before going into battle" [syn: {portent}, {presage}, {prognostic},
          {prognostication}, {prodigy}]

omen
     v : indicate by signs; "These signs bode bad news" [syn: {bode},
          {portend}, {auspicate}, {prognosticate}, {presage}, {betoken},
          {foreshadow}, {augur}, {foretell}, {prefigure}, {forecast},
          {predict}]