ceaseless
1. [ adjective ] uninterrupted in time and indefinitely long continuing
Synonyms: incessant never-ending perpetual unceasing unremitting constant
Examples:

"the ceaseless thunder of surf" "in constant pain" "the incessant noise of the city" "the never-ending search for happiness" "the perpetual struggle to maintain standards in a democracy"

Related terms: continuous
Similar spelling:   ceaselessly
  causeless