reactant
UK: riˈæktənt | US: riˈæktənt
n. a substance that takes part in and undergoes change during a chemical reaction
The word "reactant" combines "react," derived from Latin re- (back, again) + agere (to do, act), with the suffix "-ant," which originates from Latin -antem (present participle ending). The term emerged in scientific contexts to describe substances that "act again" or participate in chemical reactions. The suffix "-ant" here functions similarly to "-er," marking the substance as an active participant in the reaction process.
Oxygen is a key reactant in the process of combustion.
The experiment measured the concentration of each reactant over time.
Without sufficient reactants, the reaction cannot proceed to completion.
Catalysts speed up reactions without being consumed as reactants.
The reactants were carefully mixed to avoid premature reaction.