The person in charge or "principal" of a school. Typically this is a British-English word and not very common in American-English. Hell most Americans probably have never heard this word before.

A Transformers toy whose robot head detached and formed a separate, smaller robot (officially, a Nebulan alien in special body armor). While the Transformer was in vehicle/animal mode, the head was required to detach and could ride inside a special compartment as the pilot. In robot mode, the head plugged into the robot's shoulders and activated a concealable display on his chest which would read out the Transformer's strenth, speed and intelligence tech spec ratings.

Compare to Targetmaster and Powermaster.