The concept of an open-universe - a theory that suggests the universe is infinite and constantly expanding - has several synonyms that capture its essence. Some of these include boundless universe, infinite cosmos, endless space, and limitless multiverse. They allude to the idea that the universe is an ever-expanding entity with no boundaries or limits, where anything is possible and there are countless potential realities. These synonyms also evoke a sense of wonder and awe, as they highlight the vastness and complexity of the universe, inspiring us to explore its secrets and mysteries. In short, the many synonyms for open-universe encapsulate the grandeur and infinite potential of the cosmos.