molecule
noun
mol·e·cule
ˈmä-li-ˌkyül 
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 honesty—
Time
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
The immune system responds by releasing molecules called pyrogens, which induce fever.
—Harry Bernheim, The Conversation, 23 May 2025
On the early Earth, however — before the rise in atmospheric oxygen due to photosynthesis — lightning may have played a crucial role in creating many prebiotic compounds, which are molecules that form the building blocks of proteins.
—Paul Sutter, Space.com, 20 May 2025
He’s enlisted a graduate student from the Sorbonne in Paris to analyze the aromatic molecules in vanilla grown in different French territories—in Réunion, New Caledonia, Tahiti and Guadeloupe in the Caribbean.
—Jay Cheshes, Smithsonian Magazine, 20 May 2025
In the process of providing energy, mitochondria produce damaging molecules, known as reactive oxygen species, that can lead to health effects such as cardiovascular disease.
—Elizabeth Landau, Quanta Magazine, 19 May 2025
See All Example Sentences for molecule
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Cite this Entry
“Molecule.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/molecule. Accessed 29 May. 2025.
Kids Definition
molecule
noun
mol·e·cule
ˈmäl-i-ˌkyü(ə)l
1
: the smallest particle of a substance having all the characteristics of the substance
a molecule of water
a molecule of oxygen
2
: a very small bit : particle
Medical Definition
molecule
noun
mol·e·cule
ˈmäl-i-ˌkyü(ə)l
: 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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