The Collaborative International Dictionary of English v.0.48:

Sift \Sift\, v. t. [imp. & p. p. Sifted; p. pr. & vb. n.
   Sifting.] [AS. siftan, from sife sieve. [root]151a. See
   Sieve.]
   1. To separate with a sieve, as the fine part of a substance
      from the coarse; as, to sift meal or flour; to sift
      powder; to sift sand or lime.
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   2. To separate or part as if with a sieve.
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            When yellow sands are sifted from below,
            The glittering billows give a golden show. --Dryden.
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   3. To examine critically or minutely; to scrutinize.
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            Sifting the very utmost sentence and syllable.
                                                  --Hooker.
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            Opportunity I here have had
            To try thee, sift thee.               --Milton.
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            Let him but narrowly sift his ideas.  --I. Taylor.
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   To sift out, to search out with care, as if by sifting.
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WordNet (r) 3.0 (2006):

sifting
    n 1: the act of separating grain from chaff; "the winnowing was
         done by women" [syn: winnow, winnowing, sifting]