The Collaborative International Dictionary of English v.0.48:

Discussion \Dis*cus"sion\, n. [L. discussio a shaking,
   examination, discussion: cf. F. discussion.]
   1. The act or process of discussing by breaking up, or
      dispersing, as a tumor, or the like. [archaic]
      [1913 Webster]

   2. The act of discussing or exchanging reasons; examination
      by argument; debate; disputation; agitation.
      [1913 Webster]

            The liberty of discussion is the great safeguard of
            all other liberties.                  --Macaulay.
      [1913 Webster]

   Discussion of a problem or Discussion of an equation
      (Math.), the operation of assigning different reasonable
      values to the arbitrary quantities and interpreting the
      result. --Math. Dict.
      [1913 Webster]

WordNet (r) 3.0 (2006):

discussion
    n 1: an extended communication (often interactive) dealing with
         some particular topic; "the book contains an excellent
         discussion of modal logic"; "his treatment of the race
         question is badly biased" [syn: discussion, treatment,
         discourse]
    2: an exchange of views on some topic; "we had a good
       discussion"; "we had a word or two about it" [syn:
       discussion, give-and-take, word]

Moby Thesaurus II by Grady Ward, 1.0:

108 Moby Thesaurus words for "discussion":
   airing, analysis, argument, article, audience, bargaining,
   bargaining session, bull session, buzz session, canvassing,
   causerie, chat, colloquium, colloquy, conclave, confab,
   confabulation, conference, confrontation, congress, consideration,
   consultation, convention, conversation, council, council fire,
   council of war, debate, debating, deliberation, descant, dialectic,
   dialogue, discourse, disquisition, dissertation, essay, etude,
   examination, exchange, exchange of views, excursus, exposition,
   eyeball-to-eyeball encounter, feature, first approach, forum,
   high-level talk, homily, huddle, interchange of views, interview,
   introductory study, investigation, joint discussion,
   logical analysis, logical discussion, lucubration, meeting, memoir,
   monograph, morceau, negotiations, news conference, note,
   open discussion, open forum, outline, palaver, pandect,
   panel discussion, paper, paragraph, parley, piece, pourparler,
   powwow, preliminary study, press conference, prolegomenon, rap,
   rap session, research paper, review, screed, scrutiny, seance,
   seminar, session, sitting, sketch, special article, study, summit,
   summit conference, summitry, survey, symposium, talk, term paper,
   theme, thesis, town meeting, tract, tractate, treatise, treatment,
   ventilation



Bouvier's Law Dictionary, Revised 6th Ed (1856):

DISCUSSION, civil law. A proceeding, on the part of a surety, by which. the
property of the principal debtor is made liable before resort can be had to
the sureties; this is called the benefit of discussion. This is the law in
Louisiana. Civ. Code of Lo. art. 3014 to 3020. See Domat, 3, 4, 1 to 4;
Burge on Sur. 329, 343, 348; 5 Toull. p. 544 7 Toull. p. 93; 2 Bouv. Inst.
n. 1414.



The Devil's Dictionary (1881-1906):

DISCUSSION, n.  A method of confirming others in their errors.