The Collaborative International Dictionary of English v.0.48:

Uncouth \Un*couth"\ ([u^]n*k[=oo]th"), a. [OE. uncouth, AS.
   unc[=u][eth] unknown, strange: un- (see Un- not) +
   c[=u][eth] known, p. p. of cunnan to know. See Can to be
   able, and cf. Unco, Unked.]
   1. Unknown. [Obs.] "This uncouth errand." --Milton.
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            To leave the good that I had in hand,
            In hope of better that was uncouth.   --Spenser.
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   2. Uncommon; rare; exquisite; elegant. [Obs.]
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            Harness . . . so uncouth and so rich. --Chaucer.
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   3. Unfamiliar; strange; hence, mysterious; dreadful; also,
      odd; awkward; boorish; as, uncouth manners. "Uncouth in
      guise and gesture." --I. Taylor.
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            I am surprised with an uncouth fear.  --Shak.
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            Thus sang the uncouth swain.          --Milton.
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   Syn: See Awkward.
        [1913 Webster] -- Un*couth"ly, adv. --
        Un*couth"ness, n.
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WordNet (r) 3.0 (2006):

uncouthness
    n 1: inelegance by virtue of being an uncouth boor [syn:
         boorishness, uncouthness]