mol·​e·​cule | \ˈmä-li-ˌkyül \

Definition of molecule 

1 : the smallest particle of a substance that retains all the properties (see property sense 1a) of the substance and is composed of one or more atoms (see atom sense 1a) a molecule of water a molecule of oxygen

2 : a tiny bit : particle a molecule of political honestyTime

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Examples of molecule in a Sentence

There is not a molecule of evidence to support these charges. not a molecule of sense in that girl

Recent Examples on the Web

Aerosols are made of sea salt, rock dust, organic material from plants and conglomerations of sulfate molecules. Helen Czerski, WSJ, "Tiny Particles That Let You See Your Breath," 11 Oct. 2018 In 1982, Marvel asked readers to send in ideas for its comics, and a fan named Randy Schueller wanted to give Spider-Man a new black costume made of unstable molecules. Alex Abad-santos, Vox, "Venom, Spider-Man’s symbiote supervillain, explained," 3 Oct. 2018 Correction: July 4, 2018 An earlier version of this article misattributed a quote about building models of molecules. Veronique Greenwood, New York Times, "It’s Time for a Chemistry Lesson. Put on Your Virtual Reality Goggles.," 3 July 2018 The device is equipped with bacteria engineered to sense particular biomolecules in the gastrointestinal tract, and it could be tailored to any number of disease-relevant molecules. David Grossman, Popular Mechanics, "Ingestible Medical Device Can Tell Your Phone What's Happening in Your Gut," 24 May 2018 Escient relies on proprietary research that has identified a previously unknown family of molecules that drugs can target. Bradley J. Fikes,, "San Diego biotech startup Escient raises $40 million," 9 May 2018 Using a 26-foot Gemini North telescope, the team of scientists studied the reflected sunlight in infrared and determined what types of molecules made up the planet's atmosphere, the release said. The Washington Post,, "Planet Uranus smells of flatulence, rotten eggs, scientists say," 24 Apr. 2018 The research team removed ovaries from the mice to induce osteoporosis and administered agave fructans, or polymers of fructose molecules, to a select portion. Sam Dangremond, Town & Country, "The Plant Used to Make Tequila Could Help Prevent Osteoporosis," 19 Apr. 2016 Like many bioluminescent animals their light is created by a reaction between the light-emitting molecule luciferin and the enzyme luciferase. National Geographic, "Living Fireworks, These Animals Produce Light Shows with Their Bodies," 30 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'molecule.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of molecule

1701, in the meaning defined at sense 1

History and Etymology for molecule

French molécule, from New Latin molecula, diminutive of Latin moles mass

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Statistics for molecule

Last Updated

15 Nov 2018

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Time Traveler for molecule

The first known use of molecule was in 1701

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More Definitions for molecule



English Language Learners Definition of molecule

: the smallest possible amount of a particular substance that has all the characteristics of that substance

: a very small amount of something


mol·​e·​cule | \ˈmä-li-ˌkyül \

Kids Definition of molecule

: the smallest portion of a substance having the properties of the substance a molecule of water


mol·​e·​cule | \ˈmäl-i-ˌkyü(ə)l \

Medical Definition of molecule 

: the smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms

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