A Boom Period is a period of economic growth and prosperity. The term 'Boom Period' can be broken down into two crossword solutions: UPS (3 letters) and HIGHS (5 letters). UPS stands for 'Uninterrupted Prosperity and Success' and HIGHS stands for 'High Income Growth and Stability'. Together, these two terms refer to a period of economic growth and stability that is sustained over a long period of time.