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
There is a molecule of evidence to support these charges.
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
Since each one of the harmful particles contains one apoB molecule, testing for it essentially captures the overall number of harmful plaque-producing compounds.
—
Akshay Syal, NBC news, 8 Feb. 2026
Free radicals are molecules that damage cells, which can lead to illness and negatively impact body function.
—Bestreviews, Chicago Tribune, 6 Feb. 2026
The bottom line is that a molecule of nitrate is a molecule of nitrate, regardless of source.
—Paul Cappiello, Louisville Courier Journal, 6 Feb. 2026
These molecules could serve as the building blocks of more complex organic molecules, which are vital in the development and sustaining of life.
—Robert Lea, Space.com, 6 Feb. 2026
See All Example Sentences for molecule
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Akshay Syal, NBC news, 8 Feb. 2026
Free radicals are molecules that damage cells, which can lead to illness and negatively impact body function.
—Bestreviews, Chicago Tribune, 6 Feb. 2026
The bottom line is that a molecule of nitrate is a molecule of nitrate, regardless of source.
—Paul Cappiello, Louisville Courier Journal, 6 Feb. 2026
These molecules could serve as the building blocks of more complex organic molecules, which are vital in the development and sustaining of life.
—Robert Lea, Space.com, 6 Feb. 2026
See All Example Sentences for molecule
Cite this Entry
“Molecule.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/molecule. Accessed 10 Feb. 2026.
Copy CitationKids 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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