A bioreactor may refer to any manufactured or engineered device or system that supports a biologically active environment.
bioreactor \bi`o*re*ac"tor\, n. an apparatus in which a suspension of microorganisms in a liquid are used to perform chemical reactions, as in synthesis of pharmaceutical agents or the conversion of harmful waste to less harmful substances. The reactor consists of a vessel to contain the suspension of microorganisms, plus a variety of attached devices used to control the reaction. [PJC]
In chemical engineering, chemical reactors are vessels designed to contain chemical reactions. One example is a pressure reactor.
chemical reactor n : an apparatus for holding substances that are undergoing a chemical reaction