The Collaborative International Dictionary of English v.0.48:

Simper \Sim"per\, v. i. [imp. & p. p. Simpered; p. pr. & vb.
   n. Simpering.] [Cf. Norw. semper fine, smart, dial. Dan.
   semper, simper, affected, coy, prudish, OSw. semper one who
   affectedly refrains from eating, Sw. sipp finical, prim, LG.
   sipp.]
   1. To smile in a silly, affected, or conceited manner.
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            Behold yond simpering dame.           --Shak.
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            With a made countenance about her mouth, between
            simpering and smiling.                --ir. P.
                                                  Sidney.
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   2. To glimmer; to twinkle. [Obs.]
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            Yet can I mark how stars above
            Simper and shine.                     --Herbert.
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The Collaborative International Dictionary of English v.0.48:

Simpering \Sim"per*ing\,
   a. & n. from Simper, v.
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Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "simpering":
   elegant, euphemistic, euphuistic, exquisite, formalistic,
   goody good-good, goody-goody, mincing, namby-pamby, overnice,
   overprecise, overrefined, pedantic, precieuse, precious, precisian,
   precisianistic, precisionistic, puristic