A unit of frequency is a measure of the number of times a periodic event occurs in a given amount of time. The crossword solutions for this term are FRESNEL (7 letters), HERTZ (5 letters), KILOHERTZ (9 letters), CPS (3 letters), and MEGAHERTZ (9 letters). FRESNEL is a unit of frequency equal to one cycle per second, while HERTZ is a unit of frequency equal to one cycle per second named after the German physicist Heinrich Hertz. KILOHERTZ is a unit of frequency equal to one thousand cycles per second, CPS is a unit of frequency equal to one cycle per second, and MEGAHERTZ is a unit of frequency equal to one million cycles per second.