Adjective/Verb + 지 않다 : This pattern is equivalent to not ~. This verb is used to negate the verb or adjective attached to it. 나지 않다 is negative form of "나다" 나다 means "happen, occur" 나지 않다 means "not happen,not occur" 나지 않는 is composed of 나지 않(다)+는 는 is a suffix used for making modifier form of present tense 끝이 나다 means "come to an end" 끝이 나지 않다 means "not come to an end" 끝이 나지 않는 means "(something) which does not come to an end" 끝이 나지 않는 전쟁 means "the war which does not come to an end"

끝이 나다 = 끝나다 = to end -지 않다 = negative 끝이 나지 않는 전쟁 = lit. a war that doesn't end > unending war