Source : Webster's Revised Unabridged Dictionary (1913)

Ambitious \Am*bi"tious\, a. [L. ambitiosus: cf. F. ambitieux.
   See {Ambition}.]
   1. Possessing, or controlled by, ambition; greatly or
      inordinately desirous of power, honor, office,
      superiority, or distinction.

            Yet Brutus says he was ambitious, And Brutus is an
            honorable man.                        --Shak.

   2. Strongly desirous; -- followed by of or the infinitive;
      as, ambitious to be or to do something.

            I was not ambitious of seeing this ceremony.
                                                  --Evelyn.

            Studious of song, and yet ambitious not to sing in
            vain.                                 --Cowper.

   3. Springing from, characterized by, or indicating, ambition;
      showy; aspiring; as, an ambitious style.

            A giant statue . . . Pushed by a wild and artless
            race, From off wide, ambitious base.  --Collins.

Source : WordNet®

ambitious
     adj 1: having a strong desire for success or achievement [ant: {unambitious}]
     2: requiring full use of your abilities or resources;
        "ambitious schedule"; "performed the most challenging task
        without a mistake" [syn: {challenging}]