The Collaborative International Dictionary of English v.0.48:

Curse \Curse\ (k?rs), v. t. [imp. & p. p. Cursed (k?rst) or
   Curst; p. pr. & vb. n. Cursing.] [AS. cursian, corsian,
   perh. of Scand. origin; cf. Dan. korse to make the sign of
   the cross, Sw. korsa, fr. Dan. & Sw. kors cross, Icel kross,
   all these Scand. words coming fr. OF. crois, croiz, fr. L.
   crux cross. Cf. Cross.]
   1. To call upon divine or supernatural power to send injury
      upon; to imprecate evil upon; to execrate.
      [1913 Webster]

            Thou shalt not . . . curse the ruler of thy people.
                                                  --Ex. xxii.
                                                  28.
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            Ere sunset I'll make thee curse the deed. --Shak.
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   2. To bring great evil upon; to be the cause of serious harm
      or unhappiness to; to furnish with that which will be a
      cause of deep trouble; to afflict or injure grievously; to
      harass or torment.
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            On impious realms and barbarous kings impose
            Thy plagues, and curse 'em with such sons as those.
                                                  --Pope.
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   To curse by bell, book, and candle. See under Bell.
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The Collaborative International Dictionary of English v.0.48:

Curst \Curst\ (k?rst),
   imp. & p. p. of Curse.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Curst \Curst\, a. [SeeCurse.]
   Froward; malignant; mischievous; malicious; snarling. [Obs.]
   [1913 Webster]

         Though his mind
         Be ne'er so curst, his tonque is kind.   --Crashaw.
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WordNet (r) 3.0 (2006):

curst
    adj 1: deserving a curse; sometimes used as an intensifier;
           "villagers shun the area believing it to be cursed";
           "cursed with four daughter"; "not a cursed drop"; "his
           cursed stupidity"; "I'll be cursed if I can see your
           reasoning" [syn: cursed, curst] [ant: blessed,
           blest]