Reactant (noun)

A substance that reacts in a chemical reaction.

Origin:

Late 19th century: from react + -ant.

Examples:

1. The chemist carefully measured out the reactants before starting the reaction.
2. The reactants in the experiment included hydrochloric acid and magnesium.
3. The reactant was a key component in the manufacturing process.
4. The reactants were carefully chosen to maximize the yield of the desired product.
5. The reactant was added drop by drop to the reaction mixture.