catalytic converter

noun

1. an antipollution device in an automotive exhaust system that contains a catalyst for chemically converting some pollutants in the exhaust gases, as carbon monoxide, unburned hydrocarbons, and oxides of nitrogen, into harmless compounds.

noun

1. a device using three-way catalysts to reduce the obnoxious and poisonous components of the products of combustion (mainly oxides of nitrogen, carbon monoxide, and unburnt hydrocarbons) from the exhausts of motor vehiclesSometimes shortened to: catcon