The Collaborative International Dictionary of English v.0.48:

Effect \Ef*fect"\, n. [L. effectus, fr. efficere, effectum, to
   effect; ex + facere to make: cf. F. effet, formerly also
   spelled effect. See Fact.]
   1. Execution; performance; realization; operation; as, the
      law goes into effect in May.
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            That no compunctious visitings of nature
            Shake my fell purpose, nor keep peace between
            The effect and it.                    --Shak.
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   2. Manifestation; expression; sign.
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            All the large effects
            That troop with majesty.              --Shak.
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   3. In general: That which is produced by an agent or cause;
      the event which follows immediately from an antecedent,
      called the cause; result; consequence; outcome; fruit; as,
      the effect of luxury.
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            The effect is the unfailing index of the amount of
            the cause.                            --Whewell.
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   4. Impression left on the mind; sensation produced.
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            Patchwork . . . introduced for oratorical effect.
                                                  --J. C.
                                                  Shairp.
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            The effect was heightened by the wild and lonely
            nature of the place.                  --W. Irving.
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   5. Power to produce results; efficiency; force; importance;
      account; as, to speak with effect.
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   6. Consequence intended; purpose; meaning; general intent; --
      with to.
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            They spake to her to that effect.     --2 Chron.
                                                  xxxiv. 22.
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   7. The purport; the sum and substance. "The effect of his
      intent." --Chaucer.

   8. Reality; actual meaning; fact, as distinguished from mere
      appearance.
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            No other in effect than what it seems. --Denham.
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   9. pl. Goods; movables; personal estate; -- sometimes used to
      embrace real as well as personal property; as, the people
      escaped from the town with their effects.
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   For effect, for an exaggerated impression or excitement.

   In effect, in fact; in substance. See 8, above.

   Of no effect, Of none effect, To no effect, or Without
   effect, destitute of results, validity, force, and the like;
      vain; fruitless. "Making the word of God of none effect
      through your tradition." --Mark vii. 13. "All my study be
      to no effect." --Shak.

   To give effect to, to make valid; to carry out in practice;
      to push to its results.

   To take effect, to become operative, to accomplish aims.
      --Shak.

   Syn: Effect, Consequence, Result.

   Usage: These words indicate things which arise out of some
          antecedent, or follow as a consequent. Effect, which
          may be regarded as the generic term, denotes that
          which springs directly from something which can
          properly be termed a cause. A consequence is more
          remote, not being strictly caused, nor yet a mere
          sequence, but following out of and following
          indirectly, or in the train of events, something on
          which it truly depends. A result is still more remote
          and variable, like the rebound of an elastic body
          which falls in very different directions. We may
          foresee the effects of a measure, may conjecture its
          consequences, but can rarely discover its final
          results.
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                Resolving all events, with their effects
                And manifold results, into the will
                And arbitration wise of the Supreme. --Cowper.
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                Shun the bitter consequence, for know,
                The day thou eatest thereof, . . . thou shalt
                die.                              --Milton.
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WordNet (r) 3.0 (2006):

in effect
    adv 1: in actuality or reality or fact; "she is effectively his
           wife"; "in effect, they had no choice" [syn:
           effectively, in effect]
    adj 1: exerting force or influence; "the law is effective
           immediately"; "a warranty good for two years"; "the law
           is already in effect (or in force)" [syn: effective,
           good, in effect(p), in force(p)]