The crossword solution for the term 'Prefix with FLOW' is UNI, which is a three-letter word. UNI is a prefix that means 'ONE' or 'SINGLE'. It is often used to describe something that is unified or singular in nature. For example, a unicycle is a SINGLE-wheeled bicycle, and a unified field theory is a SINGLE theory that explains all physical phenomena. When combined with the word 'FLOW', UNI can refer to a SINGLE, continuous FLOW of something, such as a river or a stream.