base region, (physical)

(1) A region that lies between an emitter and a collector of a transistor and into which minority carriers are injected. (Ref. 60 IRE 28.S1.)

(2) The physical region that is located between the collector junction and the emitter junction and contains the control region

References: 

JESD10, 9/81

JESD77-B, 2/00