WordWeb Online

1. Having a strong desire for success or achievement
   "The Group of Eight rich nations will likely agree to an ambitious target for cutting greenhouse costs";
   - aspirational
    
2. Requiring full use of your abilities or resources
   "ambitious schedule";
   - challenging

See also: ambition, ambitiousness, aspirant, aspiring, compulsive, determined, difficult, driven, enterprising, go-getting [informal], hard, manqué, overambitious, pushful, pushy, wishful, would-be

Antonym: unambitious

Encyclopedia: Ambitious