The term 'lasting forever' can be described in many ways, and the crossword solutions provide a variety of words to express this concept. Eonian (6 letters) is an adjective meaning lasting for an immeasurably long time, while IMMORTAL (8 letters) is an adjective meaning not subject to death or decay. ETERNAL (7 letters) is an adjective meaning having no beginning and no end, and UNDYING (7 letters) is an adjective meaning never ceasing or ending. AGELESS (7 letters) is an adjective meaning having no particular age, and ENDLESS (7 letters) is an adjective meaning having no end. All of these words describe the concept of lasting forever in different ways.