When two people engage in anal sex.

(called "assmosis" because the two lovers are absorbing each other's pleasure as they bump their ends)

Derived from the word "osmosis."
Okay cowboy, let's go make love on the couch via assmosis.
by Mark H May 22, 2004
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The process of previous farts in a seat, chair, couch, etc reverse cycling up someone’s butt and being farted again.
Dude, someone must have been ripping ass in this seat because I’ve got some serious reverse assmosis going on right now.
by BDE84 July 20, 2018
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the process of one's butt getting bigger just by standing beside those with bigger butts.
People with fat friends get bigger butts just by being around "fat asses"
Julie's butt got bigger every time she was near Jane because of assmosis.
I can't help that my ass has gotten bigger; it was assmosis.
by Serena Peterson October 02, 2007
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the gradual or unconscious assimilation of ideas while sitting on one's posterior in a classroom setting
While sitting and listening to the long lecture I seem to have retained much of the content by the process of assmosis.
by herbybell April 03, 2010
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the process of one's butt getting bigger just by standing beside those with bigger butts.
People with fat friends get bigger butts just by being around "fat asses"
Julie's butt got bigger every time she was near Jane because of assmosis.
I can't help that my ass has gotten bigger; it was assmosis.
by Serena Peterson November 28, 2007
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It’s when a shit sits in a toilet bowl for too long and starts to dissolve and turn to shit water.
AJ: My fucking roommate left a shit in the bathroom this morning and I think it was clogged. I swear when I come back, it better not be there.
Isaiah: Nah, it’ll be shit water. What’s the term? Osmosis?
AJ: Assmosis
by MotherfuckingSatan August 27, 2019
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