Source : Webster's Revised Unabridged Dictionary (1913)

Ominous \Om"i*nous\, a. [L. ominosus, fr. omen. See {Omen}.]
   Of or pertaining to an omen or to omens; being or exhibiting
   an omen; significant; portentous; -- formerly used both in a
   favorable and unfavorable sense; now chiefly in the latter;
   foreboding or foreshowing evil; inauspicious; as, an ominous
   dread.

         He had a good ominous name to have made a peace.
                                                  --Bacon.

         In the heathen worship of God, a sacrifice without a
         heart was accounted ominous.             --South.
   -- {Om"i*nous*ly}, adv. -- {Om"i*nous*ness}, n.