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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

Chemistry - Introductory

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Chemical Reactions - Introductory

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Chemistry - High School

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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.

Reactant, catalyst: All the ingredients are there for personal transformation.

From Los Angeles Times • Nov. 10, 2020

Viewing the diagram from left to right, the system initially comprises reactants only, A + B. Reactant molecules with sufficient energy can collide to form a high-energy activated complex or transition state.

From Textbooks • Feb. 14, 2019

"Reactant feeding at D-9 rate," said Barret after a split-second pause.

From Sabotage in Space by Glanzman, Louis

"Reactant feeding at D-9 rate, sir," he reported.

From On the Trail of the Space Pirates by Glanzman, Louis

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.