The Collaborative International Dictionary of English v.0.48:

Conspire \Con*spire"\, v. t.
   To plot; to plan; to combine for.
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         Angry clouds conspire your overthrow.    --Bp. Hall.
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The Collaborative International Dictionary of English v.0.48:

Conspire \Con*spire"\ (k[o^]n*sp[imac]r"), v. i. [imp. & p. p.
   Conspired (k[o^]n*sp[imac]rd"); p. pr. & vb. n.
   Conspiring.] [F. conspirer, L. conspirare to blow together,
   harmonize, agree, plot; con- + spirare to breathe, blow. See
   Spirit.]
   1. To make an agreement, esp. a secret agreement, to do some
      act, as to commit treason or a crime, or to do some
      unlawful deed; to plot together.
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            They conspired against [Joseph] to slay him. --Gen.
                                                  xxxvii. 18.
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            You have conspired against our royal person,
            Joined with an enemy proclaimed.      --Shak.
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   2. To concur to one end; to agree.
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            The press, the pulpit, and the stage
            Conspire to censure and expose our age. --Roscommon.

   Syn: To unite; concur; complot; confederate; league.
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WordNet (r) 3.0 (2006):

conspire
    v 1: engage in plotting or enter into a conspiracy, swear
         together; "They conspired to overthrow the government"
         [syn: conspire, cabal, complot, conjure,
         machinate]
    2: act in unison or agreement and in secret towards a deceitful
       or illegal purpose; "The two companies conspired to cause the
       value of the stock to fall" [syn: conspire, collude]