1. pretentious creating an appearance of importance or distinction
  2. opportunity a possibility from a favorable combination of circumstances
  3. opportunity cost cost in terms of foregoing alternatives
  4. opportunistic taking advantage of any circumstance of possible benefit
  5. opportunist a person who places expediency above principle
  6. opportuneness timely convenience
  7. actinide series (chemistry) a series of 15 radioactive elements with increasing atomic numbers from actinium to lawrencium
  8. portentous of momentous or ominous significance
  9. pretentiousness the quality of being pretentious
  10. opportunism taking advantage of favorable circumstances selfishly
  11. unpretentiousness the quality of being natural and without pretensions
  12. operating surgeon a physician who specializes in surgery
  13. supporting players a cast other than the principals
  14. Upper Tunguska a river in southeastern Siberia that flows northwest from Lake Baikal to become a tributary of the Yenisei River
  15. important person a person whose actions and opinions strongly influence the course of events
  16. subordinate clause a clause in a complex sentence that cannot stand alone as a complete sentence and that functions within the sentence as a noun or adjective or adverb
  17. opportunistic infection any infection caused by a microorganism that does not normally cause disease in humans; occurs in persons with abnormally functioning immune systems (as AIDS patients or transplant patients receiving immunosuppressive drugs)
  18. ardent spirits strong distilled liquor or brandy
  19. operating system (computer science) software that controls the execution of computer programs and may provide various services
  20. important-looking impressive in appearance