USB modem vs dongle

USB modem

noun
  • A type of wireless modem which connects a computer with internet over a USB port. 

dongle

noun
  • A hardware device utilized by a specific application for purposes of copy protection. 

  • Any small device that plugs into an electronic device, typically a computer, and alters its functionality. Common examples include wireless modems, digital media players, software copy protect devices, and adapters. 

How often have the words USB modem and dongle occurred in a corpus of books? (source: Google Ngram Viewer )