1.Definition: continuing forever or indefinitely

"Hell's perpetual fires"

Related Adjective(s):aeonian, ageless, eonian, eternal, everlasting, unceasing, unending

2.Definition: uninterrupted in time and indefinitely long continuing

"The perpetual struggle to maintain standards in a democracy"

Related Adjective(s):ceaseless, constant, incessant, unceasing, unremitting