The Collaborative International Dictionary of English v.0.48:

Temper \Tem"per\, v. t. [imp. & p. p. Tempered; p. pr. & vb.
   n. Tempering.] [AS. temprian or OF. temper, F. temp['e]rer,
   and (in sense 3) temper, L. temperare, akin to tempus time.
   Cf. Temporal, Distemper, Tamper.]
   1. To mingle in due proportion; to prepare by combining; to
      modify, as by adding some new element; to qualify, as by
      an ingredient; hence, to soften; to mollify; to assuage;
      to soothe; to calm.
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            Puritan austerity was so tempered by Dutch
            indifference, that mercy itself could not have
            dictated a milder system.             --Bancroft.
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            Woman! lovely woman! nature made thee
            To temper man: we had been brutes without you.
                                                  --Otway.
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            But thy fire
            Shall be more tempered, and thy hope far higher.
                                                  --Byron.
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            She [the Goddess of Justice] threw darkness and
            clouds about her, that tempered the light into a
            thousand beautiful shades and colors. --Addison.
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   2. To fit together; to adjust; to accomodate.
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            Thy sustenance . . . serving to the appetite of the
            eater, tempered itself to every man's liking.
                                                  --Wisdom xvi.
                                                  21.
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   3. (Metal.) To bring to a proper degree of hardness; as, to
      temper iron or steel.
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            The tempered metals clash, and yield a silver sound.
                                                  --Dryden.
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   4. To govern; to manage. [A Latinism & Obs.]
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            With which the damned ghosts he governeth,
            And furies rules, and Tartare tempereth. --Spenser.
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   5. To moisten to a proper consistency and stir thoroughly, as
      clay for making brick, loam for molding, etc.
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   6. (Mus.) To adjust, as the mathematical scale to the actual
      scale, or to that in actual use.
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   Syn: To soften; mollify; assuage; soothe; calm.
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The Collaborative International Dictionary of English v.0.48:

Tempered \Tem"pered\, a.
   Brought to a proper temper; as, tempered steel; having (such)
   a temper; -- chiefly used in composition; as, a good-tempered
   or bad-tempered man; a well-tempered sword.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tempered
    adj 1: made hard or flexible or resilient especially by heat
           treatment; "a sword of tempered steel"; "tempered glass"
           [syn: tempered, treated, hardened, toughened]
           [ant: unhardened, untempered]
    2: adjusted or attuned by adding a counterbalancing element;
       "criticism tempered with kindly sympathy" [ant: untempered]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "tempered":
   aged, annealed, chastened, conditioned, constrained, controlled,
   developed, full-blown, full-fledged, full-grown, fully developed,
   hardened, heat-treated, hedged, hedged about, hushed, in control,
   in full bloom, in hand, leavened, limited, mature, mellow,
   mellowed, mitigated, modified, modulated, qualified, quelled,
   restrained, restricted, ripe, seasoned, softened, stable, subdued,
   toughened