General English

General Science

  • noun something which gives extra help or support


  • noun a device which increases the force or amount of something

Cars & Driving

  • noun an amplifier unit which increases the audio signal level at the loudspeakers, fitted between the radio or stereo unit and the speakers, often mounted in the boot


  • Any device that increases the power, force, or pressure produced by a system.


  • A device which increases, amplifies, or reinforces.
  • An amplifier of weak signals. Also called booster amplifier (1).
  • An amplifier which amplifies and retransmits RF signals. Also called booster amplifier (2).

Media Studies

  • noun a radio frequency amplifier that strengthens weak television or radio signals


  • noun a repeat injection of vaccine given some time after the first injection to maintain the immunising effect