The Collaborative International Dictionary of English v.0.48:

Temperament \Tem"per*a*ment\, n. [L. temperamentum a mixing in
   due proportion, proper measure, temperament: cf. F.
   temp['e]rament. See Temper, v. t.]
   1. Internal constitution; state with respect to the relative
      proportion of different qualities, or constituent parts.
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            The common law . . . has reduced the kingdom to its
            just state and temperament.           --Sir M. Hale.
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   2. Due mixture of qualities; a condition brought about by
      mutual compromises or concessions. [Obs.]
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            However, I forejudge not any probable expedient, any
            temperament that can be found in things of this
            nature, so disputable on their side.  --Milton.
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   3. The act of tempering or modifying; adjustment, as of
      clashing rules, interests, passions, or the like; also,
      the means by which such adjustment is effected.
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            Wholesome temperaments of the rashness of popular
            assemblies.                           --Sir J.
                                                  Mackintosh.
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   4. Condition with regard to heat or cold; temperature. [Obs.]
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            Bodies are denominated "hot" and "cold" in
            proportion to the present temperament of that part
            of our body to which they are applied. --Locke.
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   5. (Mus.) A system of compromises in the tuning of organs,
      pianofortes, and the like, whereby the tones generated
      with the vibrations of a ground tone are mutually modified
      and in part canceled, until their number reduced to the
      actual practicable scale of twelve tones to the octave.
      This scale, although in so far artificial, is yet closely
      suggestive of its origin in nature, and this system of
      tuning, although not mathematically true, yet satisfies
      the ear, while it has the convenience that the same twelve
      fixed tones answer for every key or scale, C[sharp]
      becoming identical with D[flat], and so on.
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   6. (Physiol.) The peculiar physical and mental character of
      an individual, in olden times erroneously supposed to be
      due to individual variation in the relations and
      proportions of the constituent parts of the body,
      especially of the fluids, as the bile, blood, lymph, etc.
      Hence the phrases, bilious or choleric temperament,
      sanguine temperament, etc., implying a predominance of one
      of these fluids and a corresponding influence on the
      temperament.
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   Equal temperament (Mus.), that in which the variations from
      mathematically true pitch are distributed among all the
      keys alike.

   Unequal temperament (Mus.), that in which the variations
      are thrown into the keys least used.
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WordNet (r) 3.0 (2006):

temperament
    n 1: your usual mood; "he has a happy disposition" [syn:
         disposition, temperament]
    2: excessive emotionalism or irritability and excitability
       (especially when displayed openly)
    3: an adjustment of the intervals (as in tuning a keyboard
       instrument) so that the scale can be used to play in
       different keys

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "temperament":
   animus, aptitude, bent, bias, body-build, brand, cast, character,
   characteristic, characteristics, chromatic scale, compass,
   complexion, composition, constituents, constitution, crasis,
   dharma, diapason, diathesis, disposition, dodecuple scale,
   eccentricity, enharmonic scale, ethos, fiber, frame, gamut, genius,
   grain, great scale, habit, hue, humor, humors, idiosyncrasy, ilk,
   inclination, individualism, individuality, kidney, kind, leaning,
   major scale, make, makeup, melodic minor, mental set, mentality,
   mettle, mind, mind-set, minor scale, mold, nature, octave scale,
   pentatonic scale, personality, physique, predilection,
   predisposition, preference, proclivity, propensity, property,
   quality, range, register, scale, set, slant, somatotype, sort,
   spirit, stamp, strain, streak, stripe, suchness, system, temper,
   tendency, tenor, tone, tuning, turn, turn of mind, twist, type,
   vein, warp, way, whole-tone scale