"A reagent /ri\u02C8e\u026Ad\u0292\u0259nt/ is a \"substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs.\" Although the terms reactant and reagent are often used interchangeably, a reactant is more specifically a \"substance that is consumed in the course of a chemical reaction\". Solvents, although they are involved in the reaction, are usually not referred to as reactants."@en . . .