Source : Webster's Revised Unabridged Dictionary (1913)

Immortal \Im*mor"tal\, n.
   One who will never cease to be; one exempt from death, decay,
   or annihilation. --Bunyan.

Immortal \Im*mor"tal\, a. [L. immortalis; pref. im- not +
   mortalis mortal: cf. F. immortel. See {Mortal}, and cf.
   {Immortelle}.]
   1. Not mortal; exempt from liability to die; undying;
      imperishable; lasting forever; having unlimited, or
      eternal, existance.

            Unto the King eternal, immortal, invisible. --1 Tim.
                                                  i. 17.

            For my soul, what can it do to that, Being a thing
            immortal as itself?                   --Shak.

   2. Connected with, or pertaining to immortability.

            I have immortal longings in me.       --Shak.

   3. Destined to live in all ages of this world; abiding;
      exempt from oblivion; imperishable; as, immortal fame.

            One of the few, immortal names, That were not born
            yo die.                               --Halleck.

   4. Great; excessive; grievous. [Obs.] --Hayward.

   {Immortal flowers}, imortelles; everlastings.

   Syn: Eternal; everlasting; never-ending; ceaseless;
        perpetual; continual; enduring; endless; imperishable;
        incorruptible; deathless; undying.

Source : WordNet®

immortal
     adj : not subject to death [ant: {mortal}]

immortal
     n 1: a person (such as an author) of enduring fame; "Shakespeare
          is one of the immortals"
     2: any supernatural being worshipped as controlling some part
        of the world or some aspect of life or who is the
        personification of a force [syn: {deity}, {divinity}, {god}]