(martial arts) The highest belt colour in various martial arts.
(martial arts) Someone who has attained the black belt in martial arts.
(figuratively, colloquial) Great skill in any field.
(management) A senior manager who is expert in one of various management systems such as Six Sigma or DMAIC and acts in a project leader or mentor role.
(US, southern) A geographic region where the residents are predominantly or exclusively African-American.