hertz

/hɜrts/
noun
  1. A unit of frequency equal to one cycle per second, used to measure waves, sound, and radio signals.
    • The Wi-Fi router operates at 2.4 gigahertz, which is billions of hertz.
    • The radio station broadcasts at a frequency of 100.5 hertz.
    • Human ears can typically hear sounds between 20 and 20,000 hertz.