The Collaborative International Dictionary of English v.0.48:

Matter \Mat"ter\, n. [OE. matere, F. mati[`e]re, fr. L. materia;
   perh. akin to L. mater mother. Cf. Mother, Madeira,
   Material.]
   1. That of which anything is composed; constituent substance;
      material; the material or substantial part of anything;
      the constituent elements of conception; that into which a
      notion may be analyzed; the essence; the pith; the
      embodiment.
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            He is the matter of virtue.           --B. Jonson.
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   2. That of which the sensible universe and all existent
      bodies are composed; anything which has extension,
      occupies space, or is perceptible by the senses; body;
      substance.
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   Note: Matter is usually divided by philosophical writers into
         three kinds or classes: solid, liquid, and gaseous.
         Solid substances are those whose parts firmly cohere
         and resist impression, as wood or stone. Liquids have
         free motion among their parts, and easily yield to
         impression, as water and wine. Gaseous substances are
         elastic fluids, called vapors and gases, as air and
         oxygen gas.
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   3. That with regard to, or about which, anything takes place
      or is done; the thing aimed at, treated of, or treated;
      subject of action, discussion, consideration, feeling,
      complaint, legal action, or the like; theme. "If the
      matter should be tried by duel." --Bacon.
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            Son of God, Savior of men! Thy name
            Shall be the copious matter of my song. --Milton.
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            Every great matter they shall bring unto thee, but
            every small matter they shall judge.  --Ex. xviii.
                                                  22.
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   4. That which one has to treat, or with which one has to do;
      concern; affair; business.
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            To help the matter, the alchemists call in many
            vanities out of astrology.            --Bacon.
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            Some young female seems to have carried matters so
            far, that she is ripe for asking advice.
                                                  --Spectator.
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   5. Affair worthy of account; thing of consequence;
      importance; significance; moment; -- chiefly in the
      phrases what matter? no matter, and the like.
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            A prophet some, and some a poet, cry;
            No matter which, so neither of them lie. --Dryden.
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   6. Inducing cause or occasion, especially of anything
      disagreeable or distressing; difficulty; trouble.
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            And this is the matter why interpreters upon that
            passage in Hosea will not consent it to be a true
            story, that the prophet took a harlot to wife.
                                                  --Milton.
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   7. Amount; quantity; portion; space; -- often indefinite.
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            Away he goes, . . . a matter of seven miles. --L'
                                                  Estrange.
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            I have thoughts to tarry a small matter. --Congreve.
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            No small matter of British forces were commanded
            over sea the year before.             --Milton.
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   8. Substance excreted from living animal bodies; that which
      is thrown out or discharged in a tumor, boil, or abscess;
      pus; purulent substance.
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   9. (Metaph.) That which is permanent, or is supposed to be
      given, and in or upon which changes are effected by
      psychological or physical processes and relations; --
      opposed to form. --Mansel.
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   10. (Print.) Written manuscript, or anything to be set in
       type; copy; also, type set up and ready to be used, or
       which has been used, in printing.
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   Dead matter (Print.), type which has been used, or which is
      not to be used, in printing, and is ready for
      distribution.

   Live matter (Print.), type set up, but not yet printed
      from.

   Matter in bar, Matter of fact. See under Bar, and
      Fact.

   Matter of record, anything recorded.

   Upon the matter, or Upon the whole matter, considering
      the whole; taking all things into view; all things
      considered.
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            Waller, with Sir William Balfour, exceeded in horse,
            but were, upon the whole matter, equal in foot.
                                                  --Clarendon.
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The Collaborative International Dictionary of English v.0.48:

Fact \Fact\ (f[a^]kt), n. [L. factum, fr. facere to make or do.
   Cf. Feat, Affair, Benefit, Defect, Fashion, and
   -fy.]
   1. A doing, making, or preparing. [Obs.]
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            A project for the fact and vending
            Of a new kind of fucus, paint for ladies. --B.
                                                  Jonson.
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   2. An effect produced or achieved; anything done or that
      comes to pass; an act; an event; a circumstance.
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            What might instigate him to this devilish fact, I am
            not able to conjecture.               --Evelyn.
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            He who most excels in fact of arms.   --Milton.
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   3. Reality; actuality; truth; as, he, in fact, excelled all
      the rest; the fact is, he was beaten.
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   4. The assertion or statement of a thing done or existing;
      sometimes, even when false, improperly put, by a transfer
      of meaning, for the thing done, or supposed to be done; a
      thing supposed or asserted to be done; as, history abounds
      with false facts.
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            I do not grant the fact.              --De Foe.
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            This reasoning is founded upon a fact which is not
            true.                                 --Roger Long.
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   Note: The term fact has in jurisprudence peculiar uses in
         contrast with law; as, attorney at law, and attorney in
         fact; issue in law, and issue in fact. There is also a
         grand distinction between law and fact with reference
         to the province of the judge and that of the jury, the
         latter generally determining the fact, the former the
         law. --Burrill --Bouvier.
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   Accessary before the fact, or Accessary after the fact.
      See under Accessary.

   Matter of fact, an actual occurrence; a verity; used
      adjectively: of or pertaining to facts; prosaic;
      unimaginative; as, a matter-of-fact narration.

   Syn: Act; deed; performance; event; incident; occurrence;
        circumstance.
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WordNet (r) 3.0 (2006):

matter of fact
    n 1: a disputed factual contention that is generally left for a
         jury to decide [syn: question of fact, matter of fact]
    2: a matter that is an actual fact or is demonstrable as a fact

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "matter of fact":
   absolute fact, accepted fact, actual fact, admitted fact,
   adventure, axiom, bald fact, bare fact, brutal fact, circumstance,
   cold fact, conceded fact, datum, demonstrable fact, empirical fact,
   episode, established fact, event, experience, fact,
   fact of experience, given fact, hap, happening, happenstance,
   hard fact, incident, indisputable fact, inescapable fact,
   matter-of-factness, naked fact, not guesswork, not opinion,
   occasion, occurrence, particular, phenomenon, plain, plainness,
   positive fact, postulate, prosaicism, prosaicness, prosaism, prose,
   prosiness, provable fact, reality, salient fact, self-evident fact,
   significant fact, simple fact, sober fact, stubborn fact, the case,
   the nitty-gritty, turn of events, undeniable fact,
   unimaginativeness, well-known fact



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

MATTER OF FACT, pleading. Matter which goes in denial of a declaration, and
Dot in avoidance of it. Bac. Ab. Pleas, &c. G 3; Hob. 127.