reactant
nounUK /riˈæk.tənt/
US /riˈæk.tənt/
A reactant is something that changes when it mixes with something else.
In the experiment, the two reactants bubbled and turned into a new gas.
OTHER MEANINGS
2. A substance that takes part in and is changed by a chemical reaction.
Oxygen is a reactant in the burning of wood.
3. Any person or thing that responds to a stimulus or action.
In the study, each reactant showed a different response to the light.
4. A starting substance listed on the left side of a chemical equation.
Hydrogen and oxygen are the reactants in the equation for water.