1. investigation an inquiry into unfamiliar or questionable activities
  2. investigating the work of inquiring into something thoroughly and systematically
  3. instigation deliberate and intentional triggering
  4. infestation the state of being invaded or overrun by parasites
  5. invitational pertaining to or characteristic of an invitation
  6. investigative designed to find information or ascertain facts
  7. instructional of or relating to or used in instruction
  8. dictionary a reference book containing an alphabetical list of words
  9. investigator someone who inquires carefully
  10. investigate conduct an inquiry of
  11. investigatory designed to find information or ascertain facts
  12. jurisdictional restricted to the geographic area under a particular jurisdiction
  13. inflectional characterized by inflections indicating grammatical distinctions
  14. invitation a request to be present or take part in something
  15. invocation the act of appealing for help
  16. insurrectional of or relating to or given to insurrection
  17. manifestation a clear appearance
  18. jurisdiction the territory within which power can be exercised
  19. navigational of or relating to navigation
  20. interdiction authoritative prohibition