The word 'forever' is often used to depict the concept of 'eternity' or 'perpetuity'. Some synonyms for the word 'forever' include 'eternal', 'endless', 'lasting' and 'perpetual'. Other synonyms that aptly describe forever are 'interminable', 'everlasting', and 'unceasing'. 'Infinite', 'unlimited' and 'boundless' are also great words that can be used in place of forever. In addition, one could use 'unceasingly' or 'unendingly' to describe the concept of 'forever'. One could also opt for using 'immortal', 'timeless', or 'never-ending' to depict the idea that something will last forever. Overall, these synonyms are an excellent way to add variety and depth to your writing.