Source : Webster's Revised Unabridged Dictionary (1913)

Hero \He"ro\, n.; pl. {Heroes}. [F. h['e]ros, L. heros, Gr. ?.]
   1. (Myth.) An illustrious man, supposed to be exalted, after
      death, to a place among the gods; a demigod, as Hercules.

   2. A man of distinguished valor or enterprise in danger, or
      fortitude in suffering; a prominent or central personage
      in any remarkable action or event; hence, a great or
      illustrious person.

            Each man is a hero and oracle to somebody.
                                                  --Emerson.

   3. The principal personage in a poem, story, and the like, or
      the person who has the principal share in the transactions
      related; as Achilles in the Iliad, Ulysses in the Odyssey,
      and [AE]neas in the [AE]neid.

            The shining quality of an epic hero.  --Dryden.

   {Hero worship}, extravagant admiration for great men, likened
      to the ancient worship of heroes.

            Hero worship exists, has existed, and will forever
            exist, universally among mankind.     --Carlyle.

Source : WordNet®

hero
     n 1: a man distinguished by exceptional courage and nobility and
          strength; "RAF pilots were the heroes of the Battle of
          Britain"
     2: the principal character in a play or movie or novel or poem
     3: someone who fights for a cause [syn: {champion}, {fighter},
        {paladin}]
     4: Greek mathematician and inventor who devised a way to
        determine the area of a triangle and who described various
        mechanical devices (first century) [syn: {Heron}, {Hero of
        Alexandria}]
     5: (classical mythology) a being of great strength and courage
        celebrated for bold exploits; often the offspring of a
        mortal and a god
     6: (Greek mythology) priestess of Aphrodite who killed herself
        when her lover Leander drowned while trying to swim the
        Hellespont to see her
     7: a large sandwich made of a long crusty roll split lengthwise
        and filled with meats and cheese (and tomato and onion and
        lettuce and condiments); different names are used in
        different sections of the United States [syn: {bomber}, {grinder},
         {hero sandwich}, {hoagie}, {hoagy}, {Cuban sandwich}, {Italian
        sandwich}, {poor boy}, {sub}, {submarine}, {submarine
        sandwich}, {torpedo}, {wedge}, {zep}]
     [also: {heroes} (pl)]

heroes
     See {hero}