a hand with the fingers clenched in the palm (as for hitting)
"He raised his fist to strike the bully."
A hand with the fingers clenched or curled inward.
"The boxer raised his fist to signal victory, unaware that a loud fart was echoing from the crowd behind him."
The act of breaking wind; fise.
In plain English: A fist is your hand when you curl all of your fingers into it so only your thumb and knuckles are showing.
"He clenched his fist in anger when he heard the news."
Usage: Use this word to describe a hand with tightly closed fingers, not as slang for flatulence which is spelled differently. It functions primarily as a concrete noun referring to either your own grip or the shape formed by clenching another person's hand.
To strike with the fist.
"After eating too much beans, he had to hold his breath so nobody would hear him fist when passing through the library."
To break wind.
Acronym of Future Infantry Soldier Technology.
"The acronym FIST stands for Future Infantry Soldier Technology in the new military equipment manual."
From Middle English fist, from Old English fȳst ("fist"), from Proto-West Germanic *fūsti, of uncertain origin. Cognates Cognate with Yola fest, hist ("fist"), Saterland Frisian Fäste, Fääste ("fist"), Central Franconian Fuus ("fist"), Cimbrian bòista, vòista ("fist"), Dutch vuist ("fist"), German Faust ("fist"), German Low German Fuust ("fist"), Luxembourgish Fauscht ("fist"), Yiddish פֿויסט (foyst, "fist"). More at five.