The noise that animate objects make when you sharply grab their neck. Most commonly found in birds and humans.
Father: Go ahead and grab it son.
Son: Ok.
Little Boy: gaaacck
Son: Haha! This is fun.
Little Boy: *gasp* aack gaaah!
po Psionics Новембар 17, 2004

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Term used by live and recording soundmen to describe old and broken audio equipment
Take that out of the rack and put it with the rest of the gack in corner
po R Caron Децембар 4, 2003

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to kill someone, something or some idea.
imma gack dat be-yotch!
po Nietzche Јул 1, 2003

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The unknown fluid or mass created as a result of decomposition.
Dude, you gotta bury that roadkill. That gack is starting to run down the hill.
po BrightApollo Март 7, 2003

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A man or women's discharge I.E. His or her cum.
I gacked all over her.Or she gacked in my mouth...
po cath boys Јун 28, 2006

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noun. - Ritalin, Concerta, Vyvance, Adderall, or any other Psycho-Stimulant ADHD Drug.
verb. - the state of mind when on any psychostimulant or adhd drug; usually one listed above
noun - Dude lets buy some Gack tonight.
verb - Dude lets get gacked out.
po ProjectDiesel Децембар 8, 2008

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expression used when a hockey player does something significant while playing in a hockey game
GACK! <insert french canadian or eastern european name here> just scored!
po JesusOfNazareth Март 6, 2004

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