unbridled - Not restrained or controlled.
Synonyms:  unchecked, uncurbed, ungoverned
Usage: My own spirits were high, and I bounded along with feelings of unbridled joy and hilarity.
malcontent - Discontented as toward authority.
Usage: The film follows three malcontent teenagers as they gather a following of like-minded peers and wreak havoc with their attempts to buck the system.
inexpugnable - Incapable of being overcome, challenged, or refuted.
Synonyms: impregnable
Usage: I felt the inexpugnable strength of common sense being insidiously menaced by this gruesome, by this insane, delusion.
eldritch - Suggesting the operation of supernatural influences.
Synonyms:  uncanny, weird, unearthly
Usage: An eldritch screech from someone—or something—in the distance sent chills down my spine.
superable - Capable of being surmounted or excelled.
Synonyms:  conquerable
Usage: Bankruptcy is unpleasant, to say the least, but it is a superable problem.