noun: (commerce) Initialism of Better Business Bureau.
noun: (physiology) Initialism of blood-brain barrier. [(anatomy) A structure in the central nervous system (CNS) that keeps various substances found in the bloodstream out of the brain while allowing in the substances essential to metabolic function, e.g. oxygen.]
noun: (cardiology) Initialism of bundle branch block. [(pathology) A heart condition in which the electrical impulses controlling the pace of the heart are not transmitted normally through either of the bundle branches.]