1. [n]  a severe interrogation (often violating the rights or privacy of individuals)
2. [n]  a former tribunal of the Roman Catholic Church (1232-1820) created to discover and suppress heresy

INQUISITION is a 11 letter word that starts with I.

1. \In`qui*si"tion\, n. [L. inquisitio : cf. F.
   inquisition. See {Inquire}, and cf. {Inquest}.]
   1. The act of inquiring; inquiry; search; examination;
      inspection; investigation.
   
            As I could learn through earnest inquisition.
                                                  --Latimer.
   
            Let not search and inquisition quail To bring again
            these foolish runaways.               --Shak.
   
   2. (Law)
      (a) Judicial inquiry; official examination; inquest.
      (b) The finding of a jury, especially such a finding under
          a writ of inquiry. --Bouvier.
   
                The justices in eyre had it formerly in charge
                to make inquisition concerning them by a jury of
                the county.                       --Blackstone.
   
   3. (R. C. Ch.) A court or tribunal for the examination and
      punishment of heretics, fully established by Pope Gregory
      IX. in 1235. Its operations were chiefly confined to
      Spain, Portugal, and their dependencies, and a part of
      Italy.
   
   

2. \In`qui*si"tion\, v. t.
   To make inquisistion concerning; to inquire into. [Obs.]
   --Milton.