(n) a system of time that is offset to make black people consistently late by aprox 30 minutes. the timezone and numerical values for the time are the same but the execution of appointments is such that black people seem to exist in a parallel world that is always behind everyone else.
I told jim to be here at 8:00PM EST but he just got her and its 8:30 already. I guess that is because he is on black time. (black time is short for black people time and is used interchangeably)