(1):

(n.) A cardinal, from one of the more considerable Roman Catholic nations, who looks after the interests of his people at Rome; also, a cardinal who has the same relation to a college, religious order, etc.

(2):

(n.) One having the care of the kingdom during the king's minority; a regent.

(3):

(n.) One who, or that which, defends or shields from injury, evil, oppression, etc.; a defender; a guardian; a patron.