The Collaborative International Dictionary of English v.0.48:

Question \Ques"tion\, v. i. [imp. & p. p. Questioned; p. pr. &
   vb. n. Questioning.] [Cf. F. questionner. See Question,
   n.]
   1. To ask questions; to inquire.
      [1913 Webster]

            He that questioneth much shall learn much. --Bacon.
      [1913 Webster]

   2. To argue; to converse; to dispute. [Obs.]
      [1913 Webster]

            I pray you, think you question with the Jew. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

questioning
    adj 1: perplexed (as if being expected to know something that
           you do not know); "he had a quizzical expression" [syn:
           questioning, quizzical]
    2: marked by or given to doubt; "a skeptical attitude"; "a
       skeptical listener" [syn: doubting, questioning,
       skeptical, sceptical]
    3: 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)]
    n 1: a request for information [syn: questioning, inquiring]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "questioning":
   Pyrrhonic, Socratic method, agnostic, answering, asking,
   bringing into question, catechetical method, catechistic,
   catechization, catechizing, challenge, communicating,
   communicational, communional, conversational, curious,
   disbelieving, dispute, distrustful, doubtful, doubting, dubious,
   examination, from Missouri, in doubt, inquiring, inquisitional,
   inquisitorial, interacting, interactional, interactive,
   intercommunicational, intercommunicative, intercommunional,
   interpellation, interresponsive, interrogation, interrogational,
   interrogative, interrogatory, investigative, leery, linguistic,
   mistrustful, mistrusting, oral, probing, pumping, query, querying,
   question, quiz, quizzical, quizzing, responsive, scrupulous,
   seeking, shy, skeptical, speech, suspecting, suspicious,
   telepathic, transmissional, unbelieving, uncertain, untrusting,
   verbal, wary