The crossword solution for the term 'THIS ___ UP' is 'END', which is a three-letter word. The term 'END' can refer to the conclusion or termination of something, such as a task, event, or journey. It can also refer to the furthest or final point of something, such as the END of a line or the END of a road. In addition, it can be used to describe the last part of something, such as the END of a book or the END of a movie.