The Collaborative International Dictionary of English v.0.48:

Jamboree \Jam`bo*ree"\, n. [Etym. uncertain. Cf. Jambone.]
   1. A noisy or unrestrained carousal or frolic; a spree.
      [Slang] --Kipling.

            A Calcutta-made pony cart had been standing in front
            of the manager's bungalow when Raja Singh started on
            his jamboree.                         --W. A.
                                                  Fraser.
      [Webster 1913 Suppl.]

   2. a large festive gathering.
      [PJC]

   3. an assembly of boy scouts, usually at the national or
      international level, including camping among the
      activities; -- a term adopted by the Boy Scouts
      organization.
      [PJC]

WordNet (r) 3.0 (2006):

jamboree
    n 1: a gay festivity [syn: gala, gala affair, jamboree,
         blowout]