The fear of unbridled ambition is nothing new in American politics.
During his years at Brown University, Jindal pursued his Catholic faith with unbridled zeal.
Cheney will explain that the unbridled expansions of executive powers following 9/11 were, in fact, presidential restraint.
late 14c., originally in figurative sense of "unrestrained, ungoverned," from un- (1) "not" + bridled (see bridle (v.)). Cf. Middle Dutch ongebreidelt. Literal sense of "not fitted with a bridle" (of horses) is not recorded before 1550s. The verb unbridle is attested from c.1400 in the literal sense; mid-15c. in the figurative sense.