from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A substance that is altered or incorporated into another substance in a chemical reaction, especially a directly reacting substance present at the initiation of the reaction.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun chemistry any of the participants present at the start of a chemical reaction

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a chemical substance that is present at the start of a chemical reaction


Sorry, no etymologies found.


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  • In current research we are developing a method for simultaneous measurement of three or four vector properties of reactive collisions, such as reactant or product relative velocities or rotational angular momenta.

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  • "What kind of reactant is Quent Miles using in that ship of yours?" asked Walters sharply.

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  • While the patent mentions a "reactant," that doesn't necessarily indicate fuel used today.

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  • The application, scooped up by our buddy Todd at TechFlash, describes a machine that would have pistons, and would even burn some kind of fuel (a "reactant" ignited by sparkplug), but would be aided by electromagnets to speed up the recovery process, and do away with the need for alternating pistons.


  • The chief method to get information about the mechanism of chemical reactions is chemical kinetics, i.e. measurements of the rate of the reaction as a function of reactant concentrations as well as its dependence on temperature, pressure and reaction medium.

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  • You know, it used to be that right-wingers were just sullen reactant haters with a hard-on for war and aristocracy.

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  • First of all, my new blue UV-reactant acrylic arrived from Hindleys.

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  • Instead of mining, crushing, and milling the reactant minerals, as discussed above, CO2 would be injected directly into the basalt formations and would react with the rock over time and at depth to form solid carbonate minerals.

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  • Thus, a large-scale mineral carbonation process needs a large mining operation to provide the reactant minerals in sufficient quantity. 50 Large volumes of solid material would also be produced, between 2.6 and 4.7 metric tons of materials per tCO2 sequestered, or 50%-100% more material to be disposed of by volume than originally mined.

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