bronchus development lobar bronchus development The biological process whose specific outcome is the progression of a lobar bronchus from an initial condition to its mature state. This process begins with the formation of the lobar bronchus and ends with the mature structure. The lobar bronchus is the major airway within the respiratory tree that starts by division of the principal bronchi on both sides and ends at the point of its own subdivision into tertiary or segmental bronchi. GO:0060482 biological_process