The Collaborative International Dictionary of English v.0.48:

Mot \Mot\ (m[=o]t), v. [Sing. pres. ind. Mot, Mote, Moot
   (m[=o]t), pl. Mot, Mote, Moote, pres. subj. Mote;
   imp. Moste.] [See Must, v.] [Obs.]
   May; must; might.
   [1913 Webster]

         He moot as well say one word as another  --Chaucer.
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         The wordes mote be cousin to the deed.   --Chaucer.
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         Men moot [i.e., one only] give silver to the poore
         freres.                                  --Chaucer.
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   So mote it be, so be it; amen; -- a phrase in some rituals,
      as that of the Freemasons.
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The Collaborative International Dictionary of English v.0.48:

Moot \Moot\, v. i.
   To argue or plead in a supposed case.
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         There is a difference between mooting and pleading;
         between fencing and fighting.            --B. Jonson.
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The Collaborative International Dictionary of English v.0.48:

Moot \Moot\, n. [AS. m[=o]t, gem[=o]t, a meeting; -- usually in
   comp.] [Written also mote.]
   1. A meeting for discussion and deliberation; esp., a meeting
      of the people of a village or district, in Anglo-Saxon
      times, for the discussion and settlement of matters of
      common interest; -- usually in composition; as, folk-moot.
      --J. R. Green.
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   2. [From Moot, v.] A discussion or debate; especially, a
      discussion of fictitious causes by way of practice.
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            The pleading used in courts and chancery called
            moots.                                --Sir T.
                                                  Elyot.
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   Moot case, a case or question to be mooted; a disputable
      case; an unsettled question. --Dryden.

   Moot court, a mock court, such as is held by students of
      law for practicing the conduct of law cases.

   Moot point, a point or question to be debated; a doubtful
      question.

   to make moot v. t. to render moot[2]; to moot[3].
      [1913 Webster +PJC]

The Collaborative International Dictionary of English v.0.48:

moot \moot\ (m[=o]t), v.
   See 1st Mot. [Obs.] --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

moot \moot\ (m[=oo]t), n. (Shipbuilding)
   A ring for gauging wooden pins.
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The Collaborative International Dictionary of English v.0.48:

Moot \Moot\, v. t. [imp. & p. p. Mooted; p. pr. & vb. n.
   Mooting.] [OE. moten, motien, AS. m[=o]tan to meet or
   assemble for conversation, to discuss, dispute, fr. m[=o]t,
   gem[=o]t, a meeting, an assembly; akin to Icel. m[=o]t, MHG.
   muoz. Cf. Meet to come together.]
   1. To argue for and against; to debate; to discuss; to
      propose for discussion.
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            A problem which hardly has been mentioned, much less
            mooted, in this country.              --Sir W.
                                                  Hamilton.
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   2. Specifically: To discuss by way of exercise; to argue for
      practice; to propound and discuss in a mock court.
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            First a case is appointed to be mooted by certain
            young men, containing some doubtful controversy.
                                                  --Sir T.
                                                  Elyot.
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   3. To render inconsequential, as having no effect on the
      practical outcome; to render academic; as, the ruling that
      the law was invalid mooted the question of whether he
      actually violated it.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Moot \Moot\, a.
   1. Subject, or open, to argument or discussion; undecided;
      debatable; mooted.
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   2. Of purely theoretical or academic interest; having no
      practical consequence; as, the team won in spite of the
      bad call, and whether the ruling was correct is a moot
      question.
      [PJC]

WordNet (r) 3.0 (2006):

moot
    adj 1: of no legal significance (as having been previously
           decided)
    2: open to argument or debate; "that is a moot question" [syn:
       arguable, debatable, disputable, moot]
    n 1: a hypothetical case that law students argue as an exercise;
         "he organized the weekly moot"
    v 1: think about carefully; weigh; "They considered the
         possibility of a strike"; "Turn the proposal over in your
         mind" [syn: consider, debate, moot, turn over,
         deliberate]

Moby Thesaurus II by Grady Ward, 1.0:

119 Moby Thesaurus words for "moot":
   abstract, academic, advance, agitate, arguable, argue, argufy,
   armchair, at issue, bandy words, bicker, bring before,
   bring forward, bring up, broach, canvass, cavil, choplogic,
   commend to attention, confutable, confuted, conjectural, contend,
   contest, contestable, contested, controversial, controvertible,
   cross swords, cut and thrust, debatable, debate, deniable,
   disbelieved, discept, discredited, disputable, dispute, disputed,
   doubtable, doubted, doubtful, dubious, dubitable, exploded,
   give and take, hassle, have it out, hypothetic, ideal, iffy,
   impractical, in dispute, in doubt, in dubio, in question,
   indefinite, introduce, join issue, launch, lay before, lock horns,
   logomachize, make a motion, mistakable, mistrusted, move, notional,
   offer a resolution, open to doubt, open to question, open up,
   pettifog, plead, polemicize, polemize, pose, posit, postulate,
   postulatory, prefer, problematic, problematical, proffer, propose,
   proposition, propound, put forth, put forward, put it to,
   questionable, questioned, quibble, recommend, refutable,
   set before, set forth, spar, speculative, start, submit, suggest,
   suppositional, suspect, suspected, suspicious, take sides,
   theoretical, thrash out, try conclusions, uncertain, undecided,
   under a cloud, under suspicion, undetermined, unresolved,
   unsettled, ventilate, wrangle



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

MOOT, English law. A term used in the inns of court, signifying the exercise
of arguing imaginary cases, which young barristers and students used to
perform at certain times, the better to be enabled by this practice to
defend their clients cases. A moot question is one which has not been
decided.