The Collaborative International Dictionary
Fist \Fist\, v. t. [imp. & p. p. Fisted; p. pr. & vb. n. Fisting.]
To strike with the fist.
--Dryden.To gripe with the fist. [Obs.]
--Shak.
Wiktionary
n. (context slang English) The sexual practice of inserting one or both hands into the vagina or rectum of one's sexual partner. vb. (present participle of fist English)
Wikipedia
Fisting, handballing, fist-fucking, brachiovaginal, or brachioproctic insertion is a sexual activity that involves inserting a hand into the vagina or rectum. Once insertion is complete, the fingers are either clenched into a fist or kept straight. Fisting may be performed without a partner, but it is most often a partnered activity.
Usage examples of "fisting".
Those who remember the Poletown neighborhood before the old Dodge Main plant was taken down recall the sight of women in babushkas buying and selling poultry in the Chene-Ferry Market and ox-shouldered line-workers fisting boilermakers in the Round Bar between shifts.
So there I was, fisting my cock and fingerfucking you, when suddenly you moaned my name.
Ross was gathering himself, his face registering a raging helplessness, hands fisting and opening, he'd been through this before that time the Herren snagged him, took his ship and dropped him into Pillory.
He was passive under her kiss, his neck limp, his hands fisting and unfisting at his sides.
Finally, after many grimaces and grinding of teeth and twitching of nose and ears and fisting and unfisting, he acknowledged the truth.