The term RPM DIAL is a combination of two words, 'RPM' and 'DIAL'. RPM stands for 'Revolutions Per Minute' and is a measure of the speed of rotation of an object. The DIAL refers to a device used to measure or adjust the speed of rotation. Together, the term RPM DIAL refers to a device used to measure or adjust the speed of rotation in terms of revolutions per minute. The crossword solution for this term is 'TACH', which is short for tachometer, a device used to measure the rotational speed of an object.