Source : WordNet®

gigahertz
     n : 1,000,000,000 periods per second [syn: {GHz}, {gigacycle per
         second}, {gigacycle}, {Gc}]

Source : Free On-Line Dictionary of Computing

GigaHertz
     
         (GHz) Billions of cycles per second.
     
        The unit of frequency used to measure the {clock rate} of
        modern {digital logic}, including {microprocessors}.
     
        (2001-05-14)