The Collaborative International Dictionary of English v.0.48:

Sough \Sough\, v. i.
   To whistle or sigh, as the wind.
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The Collaborative International Dictionary of English v.0.48:

Sough \Sough\, n.
   A sow. [Obs.] --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Sough \Sough\, n. [Etymol. uncertain.]
   A small drain; an adit. [Prov. Eng.] --W. M. Buchanan.
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The Collaborative International Dictionary of English v.0.48:

Sough \Sough\ (?; 277), n. [Cf. Icel. s?gr (in comp.) a rushing
   sound, or OE. swough, swogh, a sound, AS. sw?gan to rustle.
   Cf. Surf, Swoon, v. i.]
   1. The sound produced by soughing; a hollow murmur or
      roaring.
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            The whispering leaves or solemn sough of the forest.
                                                  --W. Howitt.
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   2. Hence, a vague rumor or flying report. [Scot.]
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   3. A cant or whining mode of speaking, especially in
      preaching or praying. [Scot.] --Jamieson.
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WordNet (r) 3.0 (2006):

sough
    v 1: make a murmuring sound; "the water was purling" [syn:
         sough, purl]