reagent

noun Chemistry.

1. a substance that, because of the reactions it causes, is used in analysis and synthesis.

noun

1. a substance for use in a chemical reaction, esp for use in chemical synthesis and analysis

n.

1785, from re- + agent “substance that produces a chemical reaction.”

n.

1. A substance used in a chemical reaction to detect, measure, examine, or produce other substances.

1. A substance participating in a chemical reaction, especially one used to detect, measure, or produce another substance. Compare agent.