It is a relationship between two sister, it is more than a best friend and means more than the word sister. If you have a sister that you are best friends with she is your Best Sister!
by Jillian Pantalone July 15, 2011
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Someone whom is your sister or someone who resembles a sister, that will always have your back and is your bestfriend at the same time
by Momma cat August 27, 2017
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An individual who identifies as a sister to another sibling, who is very clearly not able to be superseded by another sister or person, from inside the family or in any other family. Since there is only one person that can hold this spot, I will save everyone some time and let you know this person identifies as Crystal Kar.....dis.
My sister does so much for me, she is the best sister ever!
Wow, I wish I was him/her, because they have the best sister ever!
by The truth 123987 January 11, 2021
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a stupid comeback phrase that's used for virtually everything, even if it doesn't make any sense whatsoever
Friend #1: dude! i saw your mom last night! she was hot!
Friend #2: your best friend's sister!
Friend #!: you have a sister!?

dude: what happened last night!?
dude 2: your best friend's sister!
dude: shut up!
by dawg69 June 21, 2009
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