ADJECTIVE (3)

1. especially indicating a form of prosecution in which proceedings are secret and the accused is questioned by a prosecutor who acts also as the judge;

2. marked by inquisitive interest; especially suggestive of an ecclesiastical inquisitor;
- Example: "the press was inquisitorial to the point of antagonism"
- Example: "a practical police force with true inquisitorial talents"- Waldo Frank

3. having the authority to conduct official investigations;
- Example: "the inquisitorial power of the Senate"

The Collaborative International Dictionary of English v.0.48:

Inquisitorial \In*quis`i*to"ri*al\, a. [Cf. F. inquisitorial.]
   1. Pertaining to inquisition; making rigorous and unfriendly
      inquiry; searching; as, inquisitorial power. "Illiberal
      and inquisitorial abuse." --F. Blackburne.
      [1913 Webster]

            He conferred on it a kind of inquisitorial and
            censorious power even over the laity, and directed
            it to inquire into all matters of conscience.
                                                  --Hume.
      [1913 Webster]

   2. Pertaining to the Court of Inquisition or resembling its
      practices. "Inquisitorial robes." --C. Buchanan.
      [1913 Webster]

WordNet (r) 3.0 (2006):

inquisitorial
    adj 1: especially indicating a form of prosecution in which
           proceedings are secret and the accused is questioned by a
           prosecutor who acts also as the judge [ant:
           accusatorial]
    2: marked by inquisitive interest; especially suggestive of an
       ecclesiastical inquisitor; "the press was inquisitorial to
       the point of antagonism"; "a practical police force with true
       inquisitorial talents"- Waldo Frank
    3: having the authority to conduct official investigations; "the
       inquisitorial power of the Senate"