Dic: Synonyms: opportunity, occasion, opening, chance, break

These nouns refer to a favorable or advantageous circumstance or combination of circumstances.

• Opportunity is an auspicious state of affairs or a suitable time:
  ... "If you prepare yourself . . . you will be able to grasp opportunity for broader experience when it appears" (Eleanor Roosevelt).
• Occasion suggests the proper time for action:
  ... an auspicious occasion; an occasion for celebration. 
• An opening is an opportunity affording a good possibility of success:
  ... waited patiently for her opening, then exposed the report's inconsistency.
• Chance often implies an opportunity that arises through luck or accident:
  ... a chance for us to chat; no chance of losing.
• A break is an often sudden piece of luck, especially good luck:
  ... got his first big break in Hollywood.

opportunity:

1(a). A favorable or advantageous circumstance or combination of circumstances.
1(b). A favorable or suitable occasion or time.
2. A chance for progress or advancement.

.... The American Heritage

CF. Dic: an opportunity (하고 싶은데 할 수 있겠다 싶은 것)