Home›Browse›R›reducerreducerOur editors are putting together more complete content — check back in about 20 minutesreducerreducer — nounnoun1. a device or substance that reduces something1.nounDefinitiona device or substance that reduces somethingExampleA reducer is used to lower the pressure of the gas.2. a fitting used to connect pipes of different sizes2.nounDefinitiona fitting used to connect pipes of different sizesExampleThe plumber installed a reducer to join the two pipes.