The Collaborative International Dictionary of English v.0.48:

Inquisitive \In*quis"i*tive\, n.
   A person who is inquisitive; one curious in research. --Sir
   W. Temple.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Inquisitive \In*quis"i*tive\, a. [OE. inquisitif, F.
   inquisitif.]
   1. Disposed to ask questions, especially in matters which do
      not concern the inquirer.
      [1913 Webster]

            A wise man is not inquisitive about things
            impertinent.                          --Broome.
      [1913 Webster]

   2. Given to examination, investigation, or research;
      searching; curious.
      [1913 Webster]

            A young, inquisitive, and sprightly genius. --I.
                                                  Watts.

   Syn: Inquiring; prying; curious; meddling; intrusive.

   Usage: Inquisitive, Curious, Prying. Curious denotes a
          feeling, and inquisitive a habit. We are curious when
          we desire to learn something new; we are inquisitive
          when we set ourselves to gain it by inquiry or
          research. Prying implies inquisitiveness, and is more
          commonly used in a bad sense, as indicating a desire
          to penetrate into the secrets of others.
          [1913 Webster]

                [We] curious are to hear,
                What happens new.                 --Milton.
          [1913 Webster]

                This folio of four pages [a newspaper], happy
                work!
                Which not even critics criticise; that holds
                Inquisitive attention, while I read. --Cowper.
          [1913 Webster]

                Nor need we with a prying eye survey
                The distant skies, to find the Milky Way.
                                                  --Creech.
          [1913 Webster]

WordNet (r) 3.0 (2006):

inquisitive
    adj 1: showing curiosity; "if someone saw a man climbing a light
           post they might get inquisitive"; "raised a speculative
           eyebrow" [syn: inquisitive, speculative,
           questioning, wondering(a)]
    2: inquiring or appearing to inquire; "an inquiring look"; "the
       police are proverbially inquisitive"

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "inquisitive":
   agape, agog, all agog, analytical, burning with curiosity, busy,
   busybody, consumed with curiosity, curious, exploring, forward,
   ghoulish, gossipy, impertinent, inquiring, inquisitorial,
   interested, intrusive, investigative, itchy, meddlesome, meddling,
   morbid, morbidly curious, nosy, officious, open-eyed, openmouthed,
   overcurious, presumptuous, probing, prurient, prying, pushing,
   pushy, questioning, quizzical, scopophiliac, searching,
   self-appointed, snooping, snoopy, supercurious, voyeuristic