The Collaborative International Dictionary of English v.0.48:

Tact \Tact\, n. [L. tactus a touching, touch, fr. tangere,
   tactum, to touch: cf. F. tact. See Tangent.]
   1. The sense of touch; feeling.
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            Did you suppose that I could not make myself
            sensible to tact as well as sight?    --Southey.
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            Now, sight is a very refined tact.    --J. Le Conte.
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   2. (Mus.) The stroke in beating time.
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   3. Sensitive mental touch; peculiar skill or faculty; nice
      perception or discernment; ready power of appreciating and
      doing what is required by circumstances.
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            He had formed plans not inferior in grandeur and
            boldness to those of Richelieu, and had carried them
            into effect with a tact and wariness worthy of
            Mazarin.                              --Macaulay.
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            A tact which surpassed the tact of her sex as much
            as the tact of her sex surpassed the tact of ours.
                                                  --Macaulay.
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WordNet (r) 3.0 (2006):

tact
    n 1: consideration in dealing with others and avoiding giving
         offense [syn: tact, tactfulness] [ant: tactlessness]

Moby Thesaurus II by Grady Ward, 1.0:

175 Moby Thesaurus words for "tact":
   ability, accommodatingness, acumen, acuteness, address, adeptness,
   adroitness, agreeableness, airmanship, allergy, amenity,
   anaphylaxis, appreciation, appreciation of differences,
   appreciativeness, artfulness, artisanship, artistic judgment,
   artistry, attentiveness, bravura, brilliance, capability, capacity,
   care, carefulness, civility, cleverness, comity, command,
   competence, complaisance, concern, connoisseurship,
   considerateness, consideration, control, coordination,
   courteousness, courtesy, craft, craftsmanship, critical niceness,
   criticalness, cunning, deference, deftness, delicacy, dexterity,
   dexterousness, dextrousness, diplomacy, discernment, discretion,
   discriminating taste, discriminatingness, discrimination,
   discriminativeness, efficiency, empathy, expertise, exquisiteness,
   facility, fastidiousness, feel, feeling, fine palate, fineness,
   finesse, gallantry, grace, gracefulness, graciousness, grip,
   handiness, head, heedfulness, helpfulness, horsemanship,
   hyperesthesia, hyperpathia, hypersensitivity, identification,
   indulgence, ingeniousness, ingenuity, irritability, judgement,
   judiciousness, know-how, leniency, making distinctions,
   marksmanship, mastership, mastery, mindfulness, nervousness,
   niceness of distinction, nicety, obligingness, oversensibility,
   oversensitiveness, overtenderness, palate, passibility, perception,
   perceptiveness, perceptivity, photophobia, poise, policy,
   politeness, politesse, politicness, practical ability, presence,
   prickliness, proficiency, prowess, prudence, quickness, readiness,
   refined discrimination, refined palate, refinement, regard,
   regardfulness, repose, resource, resourcefulness, respect,
   respectfulness, responsiveness, savoir faire, savoir-faire, savvy,
   seamanship, selectiveness, sense, sensibility, sensitiveness,
   sensitivity, sensitization, skill, skillfulness, smoothness,
   solicitousness, solicitude, soreness, style, suavity, subtlety,
   supersensitivity, sympathy, tactfulness, taste,
   technical brilliance, technical mastery, technical skill,
   technique, tenderness, tetchiness, thin skin, thought,
   thoughtfulness, ticklishness, timing, toleration, touchiness,
   understanding, urbanity, virtuosity, wit, wizardry, workmanship