"For ever" is a phrase that suggests an everlasting or indefinite period of time. However, there are several other synonyms that can be used to convey the same meaning. Eternal is a word used to describe something that is forever and ever. Perpetual means something that never ends or continues indefinitely. Incessant is another synonym that suggests something that goes on without interruption or forever. Endless, infinite and unceasing are a few more synonyms that can replace "for ever". Undying, unending and everlasting are other words with which "for ever" can be replaced. Therefore, one can always choose amongst these synonyms to add more variety to their writing or speaking.