(1):

(v. i.) Pertaining to rebels or rebellion; acting in revolt; rebellious; as, rebel troops.

(2):

(v. i.) To renounce, and resist by force, the authority of the ruler or government to which one owes obedience. See Rebellion.

(3):

(v. i.) To be disobedient to authority; to assume a hostile or insubordinate attitude; to revolt.

(4):

(n.) One who rebels.