The Collaborative International Dictionary of English v.0.48:

Initiation \In*i`ti*a"tion\, n. [L. initiatio: cf. F.
   initiation.]
   [1913 Webster]
   1. The act of initiating, or the process of being initiated
      or introduced; as, initiation into a society, into
      business, literature, etc. "The initiation of courses of
      events." --Pope.
      [1913 Webster]

   2. The form or ceremony by which a person is introduced into
      any society; mode of entrance into an organized body;
      especially, the rite of admission into a secret society or
      order.
      [1913 Webster]

            Silence is the first thing that is taught us at our
            initiation into sacred mysteries.     --Broome.
      [1913 Webster]

WordNet (r) 3.0 (2006):

initiation
    n 1: a formal entry into an organization or position or office;
         "his initiation into the club"; "he was ordered to report
         for induction into the army"; "he gave a speech as part of
         his installation into the hall of fame" [syn: initiation,
         induction, installation]
    2: the act of starting something for the first time; introducing
       something new; "she looked forward to her initiation as an
       adult"; "the foundation of a new scientific society" [syn:
       initiation, founding, foundation, institution,
       origination, creation, innovation, introduction,
       instauration]
    3: wisdom as evidenced by the possession of knowledge; "his
       knowledgeability impressed me"; "his dullness was due to lack
       of initiation" [syn: knowledgeability, knowledgeableness,
       initiation]
    4: an act that sets in motion some course of events [syn:
       trigger, induction, initiation]