The Collaborative International Dictionary of English v.0.48:

Blight \Blight\ (bl[imac]t), v. t. [imp. & p. p. Blighted; p.
   pr. & vb. n. Blighting.] [Perh. contr. from AS.
   bl[imac]cettan to glitter, fr. the same root as E. bleak. The
   meaning "to blight" comes in that case from to glitter,
   hence, to be white or pale, grow pale, make pale, bleach. Cf.
   Bleach, Bleak.]
   1. To affect with blight; to blast; to prevent the growth and
      fertility of.
      [1913 Webster]

            [This vapor] blasts vegetables, blights corn and
            fruit, and is sometimes injurious even to man.
                                                  --Woodward.
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   2. Hence: To destroy the happiness of; to ruin; to mar
      essentially; to frustrate; as, to blight one's prospects.
      [1913 Webster]

            Seared in heart and lone and blighted. --Byron.
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The Collaborative International Dictionary of English v.0.48:

Blight \Blight\, v. i.
   To be affected by blight; to blast; as, this vine never
   blights.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Blight \Blight\, n.
   1. Mildew; decay; anything nipping or blasting; -- applied as
      a general name to various injuries or diseases of plants,
      causing the whole or a part to wither, whether occasioned
      by insects, fungi, or atmospheric influences.
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   2. The act of blighting, or the state of being blighted; a
      withering or mildewing, or a stoppage of growth in the
      whole or a part of a plant, etc.
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   3. That which frustrates one's plans or withers one's hopes;
      that which impairs or destroys.
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            A blight seemed to have fallen over our fortunes.
                                                  --Disraeli.
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   4. (Zool.) A downy species of aphis, or plant louse,
      destructive to fruit trees, infesting both the roots and
      branches; -- also applied to several other injurious
      insects.
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   5. pl. A rashlike eruption on the human skin. [U. S.]
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WordNet (r) 3.0 (2006):

blight
    n 1: a state or condition being blighted
    2: any plant disease resulting in withering without rotting
    v 1: cause to suffer a blight; "Too much rain may blight the
         garden with mold" [syn: blight, plague]

Moby Thesaurus II by Grady Ward, 1.0:

218 Moby Thesaurus words for "blight":
   abnormality, abomination, abuse, acute disease,
   adverse circumstances, adversity, affection, afflict, affliction,
   aggravation, aggrieve, ailment, allergic disease, allergy,
   annoyance, atrocity, atrophy, bacterial disease, bad, bane, befoul,
   befoulment, bewitch, birth defect, blast, blast-freeze, botch,
   bummer, calamity, cancer, canker, cardiovascular disease, care,
   chronic disease, circulatory disease, complaint, complication,
   condemn, condition, congeal, congenital defect, corrupt,
   corruption, cross, crucify, crying evil, curse, damage, dash,
   defect, deficiency disease, defile, defilement, deformity,
   degenerative disease, deprave, despoil, despoliation, destroy,
   destruction, detriment, difficulties, difficulty, disability,
   disadvantage, disease, disorder, disserve, distemper, distress,
   do a mischief, do evil, do ill, do wrong, do wrong by, doom,
   downer, dry rot, endemic, endemic disease, endocrine disease,
   envenom, epidemic disease, evil, freeze, freeze solid,
   functional disease, fungus, fungus disease,
   gastrointestinal disease, genetic disease, get into trouble,
   glaciate, glacify, grievance, handicap, harass, hard knocks,
   hard life, hard lot, hardcase, hardship, harm, havoc,
   hereditary disease, hex, hurt, iatrogenic disease, ice, ill,
   illness, impair, indisposition, infect, infection,
   infectious disease, infest, infestation, infirmity, injure, injury,
   irritation, jinx, malady, malaise, maltreat, mar, menace, mildew,
   mischief, misfortune, mistreat, mold, molest, morbidity, morbus,
   moth, moth and rust, muscular disease, must, neurological disease,
   nip, nutritional disease, occupational disease, organic disease,
   outrage, pandemic disease, pathological condition, pathology,
   persecute, pest, pestilence, plague, plant disease,
   play havoc with, play hob with, plight, poison, pollute, pollution,
   predicament, prejudice, pressure, protozoan disease,
   psychosomatic disease, quick-freeze, refreeze, regelate,
   respiratory disease, rigor, rockiness, rot, ruin, rust, savage,
   scathe, scourge, sea of troubles, secondary disease, seediness,
   sickishness, sickness, signs, smut, spoil, stress, stress of life,
   symptomatology, symptomology, symptoms, syndrome, taint, the pip,
   the worst, threaten, torment, torture, toxin, trial, tribulation,
   trouble, troubles, urogenital disease, vale of tears, venom,
   vexation, vicissitude, violate, virus disease, wasting disease,
   wither, woe, worm, worm disease, wound, wreak havoc on, wreck,
   wrong