The crossword solution for the term PERPETUAL is ETERNE, which is a six-letter word. PERPETUAL means something that is ongoing or continuous without end. It is often used to describe something that lasts forever or is infinite. ETERNE is an adjective that is derived from the Latin word 'aeternus, ' which means eternal or everlasting. Therefore, ETERNE is a synonym for PERPETUAL, and it can be used to describe something that is ongoing and never-ending.