The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, v. t. [F. teint, p. p. of teindre to dye, tinge,
   fr. L. tingere, tinctum. See Tinge, and cf. Tint.]
   1. To imbue or impregnate with something extraneous,
      especially with something odious, noxious, or poisonous;
      hence, to corrupt; to infect; to poison; as, putrid
      substance taint the air.
      [1913 Webster]

   2. Fig.: To stain; to sully; to tarnish.
      [1913 Webster]

            His unkindness may defeat my life,
            But never taint my love.              --Shak.
      [1913 Webster]

   Syn: To contaminate; defile; pollute; corrupt; infect;
        disease; vitiate; poison.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, n. [Cf. F. atteinte a blow, bit, stroke. See
   Attaint.]
   1. A thrust with a lance, which fails of its intended effect.
      [Obs.]
      [1913 Webster]

            This taint he followed with his sword drawn from a
            silver sheath.                        --Chapman.
      [1913 Webster]

   2. An injury done to a lance in an encounter, without its
      being broken; also, a breaking of a lance in an encounter
      in a dishonorable or unscientific manner. [Obs.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, v. i.
   1. To be infected or corrupted; to be touched with something
      corrupting.
      [1913 Webster]

            I can not taint with fear.            --Shak.
      [1913 Webster]

   2. To be affected with incipient putrefaction; as, meat soon
      taints in warm weather.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, n.
   1. Tincture; hue; color; tinge. [Obs.]
      [1913 Webster]

   2. Infection; corruption; deprivation.
      [1913 Webster]

            He had inherited from his parents a scrofulous
            taint, which it was beyond the power of medicine to
            remove.                               --Macaulay.
      [1913 Webster]

   3. A blemish on reputation; stain; spot; disgrace.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, v. i. [imp. & p. p. Tainted; p. pr. & vb. n.
   Tainting.]
   To thrust ineffectually with a lance. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, v. t.
   1. To injure, as a lance, without breaking it; also, to
      break, as a lance, but usually in an unknightly or
      unscientific manner. [Obs.]
      [1913 Webster]

            Do not fear; I have
            A staff to taint, and bravely.        --Massinger.
      [1913 Webster]

   2. To hit or touch lightly, in tilting. [Obs.]
      [1913 Webster]

            They tainted each other on the helms and passed by.
                                                  --Ld. Berners.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Taint \Taint\, v. t.
   Aphetic form of Attaint.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

taint
    n 1: the state of being contaminated [syn: contamination,
         taint]
    v 1: place under suspicion or cast doubt upon; "sully someone's
         reputation" [syn: defile, sully, corrupt, taint,
         cloud]
    2: contaminate with a disease or microorganism [syn: infect,
       taint] [ant: disinfect]

Moby Thesaurus II by Grady Ward, 1.0:

302 Moby Thesaurus words for "taint":
   abuse, adulterate, aerial infection, afflict, aggrieve,
   airborne infection, alloy, aroma, aspersion, attaint, attribute,
   badge, badge of infamy, bar sinister, baton, bedaub, befoul,
   benasty, bend sinister, besmear, besmirch, besmoke, bespatter,
   bestain, bewitch, black eye, black mark, blacken, blemish, blight,
   bloodstain, blot, blotch, blow upon, blur, brand, broad arrow, bug,
   cachet, canker, carrier, cast, catch, censure, champain, character,
   characteristic, cheapen, cloud, coarsen, communicability, condemn,
   configuration, confound, contagion, contagiousness, contaminate,
   contamination, corrupt, crack, crucify, cryptogenic infection,
   curse, cut, dab, damage, darken, dash, daub, debase, debauch,
   defame, defect, defection, deficiency, defile, deflower,
   degenerate, degrade, denature, deprave, desecrate, despoil,
   destroy, devalue, differentia, differential, direct infection,
   dirty, disadvantage, disapprove, discolor, discredit, disease,
   dishonor, disparage, disparagement, disserve, distinctive feature,
   distort, distress, do a mischief, do evil, do ill, do wrong,
   do wrong by, doom, drawback, droplet infection, dust infection,
   earmark, envenom, epidemiology, expose, expose to infamy, eyesore,
   failing, failure, fault, faute, feature, figure, flavor, flaw,
   fleck, flick, flyspeck, foible, foul, frailty, get into trouble,
   gibbet, gust, hallmark, hand infection, hang in effigy, harass,
   harm, hex, hint, hole, hurt, idiocrasy, idiosyncrasy, impair,
   imperfection, impress, impression, imputation, inadequacy, index,
   indirect infection, individualism, infect, infection,
   infectiousness, infirmity, infusion, injure, inkling, intimation,
   jinx, keynote, kink, lineaments, little problem, macula,
   maculation, macule, maltreat, mannerism, mark, mark of Cain,
   marking, menace, mess, mess up, mistreat, misuse, mold, molest,
   muddy, nasty, nature, odor, onus, outrage, particularity, patch,
   peculiarity, persecute, pervert, phytogenic infection, pillory,
   pillorying, play havoc with, play hob with, point champain, poison,
   pollute, prejudice, primary infection, problem, property,
   prostitute, pyogenic infection, quality, quirk, ravage, ravish,
   reflection, reprimand, reproach, rift, ruin, sauce, savage, savor,
   scar, scathe, scorch, seal, sear, seasoning, secondary infection,
   shade, shape, shortcoming, singe, singularity, slubber, slur,
   smack, smear, smirch, smoke, smouch, smudge, smut, smutch, snag,
   soil, something missing, soupcon, spatter, specialty, speck,
   speckle, spice, splash, splatter, splotch, spoil, spot, sprinkling,
   stain, stamp, stigma, stigmatism, stigmatization, stigmatize,
   subclinical infection, suggestion, sully, suspicion, tang, tar,
   tarnish, taste, tempering, thought, threaten, tinct, tincture,
   tinge, tint, token, torment, torture, touch, trace, trait, trick,
   twist, ulcerate, vector, vestige, vilify, violate, virus, vitiate,
   vulgarize, vulnerable place, warp, waterborne infection, weak link,
   weak point, weakness, wound, wreak havoc on, wrong,
   zoogenic infection