The Collaborative International Dictionary of English v.0.48:

Probe \Probe\, v. t. [imp. & p. p. Probed; p. pr. & vb. n.
   Probing.] [L. probare to try, examine. See Prove.]
   [1913 Webster]
   1. To examine, as a wound, an ulcer, or some cavity of the
      body, with a probe.
      [1913 Webster]

   2. Fig.: to search to the bottom; to scrutinize or examine
      thoroughly. --Dryden.
      [1913 Webster]

            The growing disposition to probe the legality of all
            acts, of the crown.                   --Hallam.
      [1913 Webster]

WordNet (r) 3.0 (2006):

probing
    adj 1: diligent and thorough in inquiry or investigation; "a
           probing inquiry"; "a searching investigation of their
           past dealings" [syn: inquisitory, probing,
           searching]