ambitious
1. [ adjective ] having a strong desire for success or achievement
Related terms: unambitious aggressive manque overambitious compulsive aspirant enterprising ambition
2. [ adjective ] requiring full use of your abilities or resources
Synonyms: challenging
Examples:

"ambitious schedule" "performed the most challenging task without a mistake"

Related terms: difficult
Similar spelling:   ambitiously
  ambition
  amphitropous
  ambitionless
  ambidextrous
  ameboid