General English

  • adjective not doing anything
  • verb to run at a low speed


  • noun the state of an engine when it is running but not delivering power to move the vehicle or aircraft
  • verb to turn over slowly without providing enough power to move the vehicle or aircraft


  • adjective not working

Cars & Driving



  • Not in use and/or not busy. Said, for instance, of a communications circuit.
  • To function at a at given operational minimum, such as a motor running without a load.
  • To be functioning under normal operating conditions, but not having an applied signal at the time. Said, for instance, of an amplifier stage during an interval in which there is no input signal. Also called quiescent (2).

Origin & History of “idle”

‘Lazy’ is only a secondary meaning of idle. It originally meant ‘useless, worthless’ (as in ‘idle threats’), and the sense ‘lazy’ did not develop until the 13th century (the Old English words for ‘lazy’ were slow and slack). Idle is shared by other west Germanic languages, and its relatives (German eitel ‘vain, futile’ and Dutch ijdel ‘vain, useless, conceited’) point up its original English meaning, but it is not known what its ultimate origins are.