An interesting and useful word. To me it suggests a bit of inappropriateness of affect, an incomplete and insincere smile, masking a bit of hidden hostility and hebetude.
"All the mirrors in the house are brought into action now: many of them after a long blank. They reflect handsome faces, simpering faces, youthful faces, faces of threescore-and-ten that will not submit to be old; the entire collection of faces that have come to pass a January week or two at Chesney Wold, and which the fashionable intelligence, a mighty hunter before the Lord, hunts with a keen scent, from their breaking cover at the Court of Saint James’s to their being run down to Death. "
From the site about Scandinavian origin words:
simper (vb) To smirk. Nor semper (fine, smart), Dan dialect semper, simper (affected, coy, prudish), O Swe semper (one who affectedly refrains from eating). Formed from O Swe sipp, simp (an affected woman). All from the notion of sipping, or taking only a little at a time, hence prudish, coy, affected, as in 'a simpering person' or a 'simpering attitude'.
