The Collaborative International Dictionary of English v.0.48:

Deduct \De*duct"\, v. t. [imp. & p. p. Deducted; p. pr. & vb.
   n. Deducting.] [L. deductus, p. p. of deducere to deduct.
   See Deduce.]
   1. To lead forth or out. [Obs.]
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            A people deducted out of the city of Philippos.
                                                  --Udall.
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   2. To take away, separate, or remove, in numbering,
      estimating, or calculating; to subtract; -- often with
      from or out of.
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            Deduct what is but vanity, or dress.  --Pope.
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            Two and a half per cent should be deducted out of
            the pay of the foreign troops.        --Bp. Burnet.
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            We deduct from the computation of our years that
            part of our time which is spent in . . . infancy.
      --Norris.
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   3. To reduce; to diminish. [Obs.] "Do not deduct it to days."
      --Massinger.
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WordNet (r) 3.0 (2006):

deduct
    v 1: make a subtraction; "subtract this amount from my paycheck"
         [syn: subtract, deduct, take off] [ant: add, add
         together]
    2: retain and refrain from disbursing; of payments; "My employer
       is withholding taxes" [syn: withhold, deduct, recoup]
    3: reason by deduction; establish by deduction [syn: deduce,
       infer, deduct, derive]