a) A shortened version of 'best friends' for internet talk.
or
b) Someone who is really close to being categorized as a best friend, but not exactly one yet.
a) TTYL bestie! XOXOX lylas!
b) Jamie: You know you're my bestie for life, girl. Arianna: WHAT, I'M NOT YOUR BEST FRIEND!!?! WHAT KIND OF RELATIONSHIP IS THIS?
Noun - A group of friends apart of the group "besties" from EAST SIDE OAKLAND not west hayward. They are all well known to each other and can relate to each other very well.
Austin has beenemo for a day, and did not want to be a bestie.