The crossword solution for the term 'superlative prefix' is UBER, which is a four-letter word. Uber is a technology company that provides a platform for ride-hailing services, food delivery, and other services. The company was founded in 2009 and is based in San Francisco, California. Uber is often used as a prefix to describe something that is of the highest quality or degree, such as an uber-luxurious car or an uber-talented musician.