When one spends an unusually large portion of time with their sister to the point where they are mistaken as a couple. However, the word gister is used with a sexual connotation.
Chris spends so much time with his gister Maddy that I'm pretty sure they are into incest.
by PeterSchwartz July 13, 2017
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One who gets the gist of a subject matter and knows enough to be dangerous with that subject in conversation or writing. One with proven gisting abilities. A gister can participate in conversations with subject experts without getting lost along the way.
Joe is such a gister — those research guys think he really has expertiseness in selective serotonin reuptake inhibition.

If it's complicated and you don't have a lot of time, ask a gister to write it.
by D L Sonders June 08, 2010
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Two sisters who are dating. This usually occurs in Alabama. There is an award winning show about two princess gisters, fighting for custody over a knight.
"Gister!"

"Gister!"
"I still love you!"
"Let's have a baby!"
by January 09, 2021
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