Unstoppable
Part of speech: adjective
Definition: Unable to be stopped.
Example sentence: They tried to humiliate and cow her down in every way possible, but Jayalalithaaji was unstoppable. With every attack, she became stronger.
Unbeatable
Part of speech: adjective
Definition: That cannot be beaten, defeated or overcome
Example sentence: The euro has become a means by which superior German productivity is able to gain an absolutely unbeatable advantage over the whole eurozone territory.