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Synonyms

reactant

American  
[ree-ak-tuhnt] / riˈæk tənt /

noun

  1. a person or thing that reacts.

  2. Also called interactant. Chemistry. any substance that undergoes a chemical change in a given reaction.


reactant British  
/ rɪˈæktənt /

noun

  1. a substance that participates in a chemical reaction, esp a substance that is present at the start of the reaction Compare product

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

reactant Scientific  
/ rē-ăk′tənt /
  1. A substance participating in a chemical reaction, especially one present at the start of the reaction.


Etymology

Origin of reactant

First recorded in 1925–30; react + -ant


Explanation

A reactant is a substance that changes in a chemical reaction. Vinegar and baking soda are reactants — when you mix them together, they bubble up and make really good lava for a model volcano. Reactants usually hang around the chemistry lab, but the concept isn't difficult if you think about the word react. When people react, they do something such as laugh at a joke or cry at sad news. In chemistry, reactants are part of something happening too: if two chemicals bond when mixed together, or if one dissolves, they are reactants. Any kind of chemical reaction involves reactants.

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Vocabulary lists containing reactant

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

By adjusting the chemical composition and pH of the reactant solutions, they altered both the size and properties of the ultrasmall openings.

From Science Daily ● Feb. 19, 2026

Furthermore, the use of conventional thin-film catalysts often results in inadequate separation of hydrogen bubbles, leading to blockages in the catalyst's active sites or hindering reactant movement, ultimately diminishing process efficiency.

From Science Daily ● Mar. 22, 2024

Once the temperature is sufficiently low, the concentration of the reactant gases on the catalyst surface increases and the reaction picks up speed again.

From Science Daily ● Oct. 5, 2023

Hydrogen ion cannot appear as a reactant because its concentration is essentially zero.

From Textbooks ● Feb. 14, 2019

Four hours later Loring and Mason came out of the reactant chamber carrying a small lead box.

From Danger in Deep Space by Louis Glanzman

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