The crossword solution for the term 'TURN ___ (BECOME)' is INTO, which is a four-letter word. The phrase 'turn INTO' is an idiom that means to become something else or to transform INTO something else. It is often used to describe a change in physical form, such as when a caterpillar turns INTO a butterfly. It can also be used to describe a change in character or behavior, such as when someone turns INTO a different person after experiencing a traumatic event.