The Collaborative International Dictionary of English v.0.48:

Smirk \Smirk\, v. i. [imp. & p. p. Smirked; p. pr. & vb. n.
   Smirking.] [OE. smirken, ASS. smercian, smearcian; cf. MHG.
   smieren, smielen, to smile. See Smile, v. i.]
   To smile in an affected or conceited manner; to smile with
   affected complaisance; to simper.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Smirk \Smirk\, n.
   A forced or affected smile; a simper.
   [1913 Webster]

         The bride, all smirk and blush, had just entered. --Sir
                                                  W. Scott.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Smirk \Smirk\, a.
   Nice,; smart; spruce; affected; simpering. "So smirk, so
   smooth." --Spenser.
   [1913 Webster]

WordNet (r) 3.0 (2006):

smirk
    n 1: a smile expressing smugness or scorn instead of pleasure
    v 1: smile affectedly or derisively [syn: smirk, simper]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "smirk":
   beam, bridle, bright smile, broad grin, crack a smile,
   ear-to-ear grin, fleer, gleaming smile, glowing smile, grimace,
   grin, grinning, idiotic grin, leer, mince, mince it, prink,
   sardonic grin, scornful laugh, simper, smile, smile brightly,
   smiling, sneer, snicker, snigger, snort, stupid grin,
   toothful grin