The term 'BOOM OR ZOOM' can be broken down into four crossword solutions: NOISE (5 letters), LENS (4 letters), SPAR (4 letters), and SONIC (5 letters). NOISE is a sound, usually loud and unpleasant, that is caused by a sudden, sharp movement of air. LENS is an optical device, typically made of glass or plastic, that is used to focus light rays in order to create an image. SPAR is a long, round pole, usually made of wood, that is used in sailing ships for support and stability. Finally, SONIC is a term used to describe sound waves that travel faster than the speed of sound. Together, these four words form the phrase 'BOOM OR ZOOM', which is often used to describe a situation that is rapidly changing or progressing.