According to the rules and usages of Parliament or of deliberative bodies; as, a parliamentary motion; parliamentary order; parliamentary procedure.

having the supreme legislative power resting with a body of cabinet ministers chosen from and responsible to the legislature or parliament; "parliamentary government"

in accord with rules and customs of a legislative or deliberative assembly; "parliamentary law"

A form of government in which the executive branch is made up of the prime minister, or premier, and that official's cabinet

A system in which the supreme legislative body is a gathering of nobility, clergy, and common people. The United Kingdom is the main example.