The Collaborative International Dictionary of English v.0.48:

Ambition \Am*bi"tion\, n. [F. ambition, L. ambitio a going
   around, especially of candidates for office is Rome, to
   solicit votes (hence, desire for office or honor), fr. ambire
   to go around. See Ambient, Issue.]
   1. The act of going about to solicit or obtain an office, or
      any other object of desire; canvassing. [Obs.]
      [1913 Webster]

            [I] used no ambition to commend my deeds. --Milton.
      [1913 Webster]

   2. An eager, and sometimes an inordinate, desire for
      preferment, honor, superiority, power, or the attainment
      of something.
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            Cromwell, I charge thee, fling a way ambition:
            By that sin fell the angels.          --Shak.
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            The pitiful ambition of possessing five or six
            thousand more acres.                  --Burke.
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The Collaborative International Dictionary of English v.0.48:

Ambition \Am*bi"tion\, v. t. [Cf. F. ambitionner.]
   To seek after ambitiously or eagerly; to covet. [R.]
   [1913 Webster]

         Pausanias, ambitioning the sovereignty of Greece,
         bargains with Xerxes for his daughter in marriage.
                                                  --Trumbull.
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WordNet (r) 3.0 (2006):

ambition
    n 1: a cherished desire; "his ambition is to own his own
         business" [syn: ambition, aspiration, dream]
    2: a strong drive for success [syn: ambition, ambitiousness]
    v 1: have as one's ambition

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "ambition":
   aim, ambitiousness, animus, anxiety, appetite, aspiration, avidity,
   basis, calling, careerism, catch, cause, climbing, consideration,
   counsel, craving, dearest wish, desideration, desideratum, design,
   desire, determination, dream, drive, eagerness, effect, energy,
   enterprise, enthusiasm, fancy, fixed purpose, forbidden fruit,
   function, get-up-and-go, glimmering goal, go-ahead, goad, goal,
   golden vision, ground, guiding light, guiding star, hope, hunger,
   idea, ideal, incentive, initiative, inspiration, intendment,
   intent, intention, keenness, lodestar, lodestone, lofty ambition,
   magnanimity, magnet, mainspring, mark, matter, meaning, mind,
   motive, nirvana, nisus, object, objective, plan, plum, point,
   power-hunger, pretension, principle, prize, project, proposal,
   prospectus, purpose, push, reason, resolution, resolve, sake,
   score, social climbing, source, spirit, spring, spur,
   status-seeking, striving, study, target, temptation, thirst,
   trophy, ulterior motive, vaulting ambition, view, vigor, vocation,
   will, wish, zeal



The Devil's Dictionary (1881-1906):

AMBITION, n.  An overmastering desire to be vilified by enemies while
living and made ridiculous by friends when dead.