Coeternity is a theological term that refers to the idea of God and the universe existing together eternally. While there are not many synonyms for this specific term, other words related to the concept of eternal existence include eternity, infinity, timeless, perpetual, and endless. These words all suggest an unending and uninterrupted existence beyond the temporal confines of human experience. In theological contexts, terms like everlasting, divine, and immortal may also be applicable. In any case, the concept of coeternity remains an intriguing and complex one that has inspired much philosophical and theological thought throughout history.