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1.
Sister or any other female relative or friend.
Sister 1: BISSTAAA
Sister 2: Bister!
Sister 3: BIisSTUhhh.
Friend: I'm a bister, too!
by bISTer June 22, 2010
 
2.
a big soul sister
I was all up in da club last night hittin on some fine bisters.
by brooke December 18, 2003