Top Definition
Sister + BFF (best friend forever), a word used for best friends who are so close they're like sisters (usually between two girls).
I haven't seen my bifster in a year & now we're finally reunited! We grew up together :))
by RosaMimosa September 16, 2012
Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from We'll never spam you.