prerogatival
/prɪˌrɒɡəˈtʌɪvl/Chiefly historical rare before late 19th cent
adjective
Of or relating to prerogative, especially (in later use) to the royal prerogative.
Origin
Early 17th century; earliest use found in James Sempill (?1566–1626), courtier and religious controversialist. From prerogative + -al.