[Definition] A system of government where an executive branch is led by a president who serves as both head of state and head of government. In such a system, this branch exists separately from the legislature, to which it is not responsible and which it cannot, in normal circumstances, dismiss. [Term] 
Presidential system
A d h o c r a c y
B a n d s o c i e t y
B u r e a u c r a c y
C h i e f d o m ( T r i b a l )
C y b e r s y n a c y
P a r l i a m e n t a r y s y s t e m
P r e s i d e n t i a l s y s t e m
N o m o c r a c y