1. Someone who at one point of your life you liked/loved and/or was very special to you (i.e. boyfriend, girlfriend, significant other, someone you dated with potential) who now is nonexistent or acts brand new.
1. "Boo, now don't you go off to Vegas with your boys for a weekend and come back acting like a once upon a time boo!"
When you love someone’s brain, and maybe love them, but don’t pursue a sexual relationship.
Usually coincides with having a spouse you can’t talk to about work or intellectual topics and you use a smart girl/guy as a conversational side piece.
Dr Meade and Harris are always talking and eating lunch together, are they hooking up?
Nah, she’s just his Big Bang boo, his wife is a kindergarten teacher.