The Collaborative International Dictionary of English v.0.48:

Smug \Smug\, a. [Of. Scand. or Low German origin; cf. LG. smuck,
   G. schmuck, Dan. smuk, OSw. smuck, sm["o]ck, and E. smock,
   smuggle; cf. G. schmuck ornament. See Smock.]
   Studiously neat or nice, especially in dress; spruce;
   affectedly precise; smooth and prim.
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         They be so smug and smooth.              --Robynson
                                                  (More's
                                                  Utopia).
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         The smug and scanty draperies of his style. --De
                                                  Quincey.
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         A young, smug, handsome holiness has no fellow. --Beau.
                                                  & Fl.
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The Collaborative International Dictionary of English v.0.48:

Smug \Smug\, v. t. [imp. & p. p. Smugged; p. pr. & vb. n.
   Smugging.]
   To make smug, or spruce. [Obs.]
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         Thus said, he smugged his beard, and stroked up fair.
                                                  --Dryton.
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WordNet (r) 3.0 (2006):

smug
    adj 1: marked by excessive complacency or self-satisfaction; "a
           smug glow of self-congratulation" [syn: smug, self-
           satisfied]