pre-noun adjectival
eternal; everlasting; endless; inexhaustible
Literary pre-noun adjectival (rentaishi) meaning something that never runs out or ends. Often used with abstract nouns like 思い, 魅力, or 泉.
尽きせぬ思いを胸に、彼は旅立った。
With endless feelings in his heart, he set off on his journey.
この街には尽きせぬ魅力がある。
This town has an inexhaustible charm.