From Longman Dictionary of Contemporary Englishamplifieram‧pli‧fi‧er /ˈæmpləfaɪə $ -faɪər/ noun [countable] 
TCRa piece of electrical equipment that makes sound louder SYN amp
TCRa piece of electrical equipment that makes sound louder SYN ampExamples from the Corpus
amplifier• They stole a television, compact disc player, an amplifier and some speakers, worth a total of £900.• Through an amplifier, the New York maintains its acoustic brightness and bluntly refuses to be anything other than a blank canvas.• Analysing the series-voltage case first, the open-circuit and loaded voltage gains of the open-loop amplifier are defined as and respectively.• There is and always has been a yawning gap at the budget end of the amplifier market.• There was no way the amplifier and these cables could live together.• Just another snooty $ 3,000 vacuum tube amplifier, I thought.• The changes might include a handicapped parking space or a phone voice amplifier.• Below is a six-channel, 600-watt amplifier. 