Definition of "simpering"

Why, look at him—look at this simpering self-righteous mug!

1892, Mark Twain [pseudonym; Samuel Langhorne Clemens], chapter XXI, in The American Claimant, New York, N.Y.: Charles L[uther] Webster & Co., page 214

I know they are supposed to be amusing, and you should be tolerant, but I wanted to swing on one, any one, anything to shatter that superior, simpering composure.

1926, Ernest Hemingway, The Sun Also Rises

I had high hopes when I moved to Spyglass, but simpering gossip on celebrity parties seems to be the closest I've gotten so far to Dad's vocation.

2004, David Mitchell, Cloud Atlas, London: Hodder and Stoughton

That sounds almost simpering. I hate sounding simpering, and over a trifling increase of four coppers on a gold, I definitely do not wish to sound simpering.

2015, L. E. Modesitt, Jr, Madness in Solidar

Well, but Polly attended, as I said; and there were strange simperings, and bowing, and courtesying, between them; the honest gentleman seeming not to know how to let his mistress wait upon him […]

1740, Samuel Richardson, Pamela; or, Virtue Rewarded