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
The team led by Paola Tiranti observed Uranus for nearly a full rotation, detecting the faint glow from molecules up to 3,100 miles (5,000 kilometres) above the cloud tops.
—
Prabhat Ranjan Mishra, Interesting Engineering, 21 Feb. 2026
Humectants are molecules that are able to bind to and retain water, which is why they are often used in lotions and moisturizers.
—Leslie Baumann, Miami Herald, 20 Feb. 2026
Blood tests showed that the men had higher levels of a molecule called interleukin-10, which switches off pain signals to the brain.
—Aria Bendix, NBC news, 20 Feb. 2026
The groups are called molecules.
—Reader Commentary, Baltimore Sun, 20 Feb. 2026
See All Example Sentences for molecule
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Prabhat Ranjan Mishra, Interesting Engineering, 21 Feb. 2026
Humectants are molecules that are able to bind to and retain water, which is why they are often used in lotions and moisturizers.
—Leslie Baumann, Miami Herald, 20 Feb. 2026
Blood tests showed that the men had higher levels of a molecule called interleukin-10, which switches off pain signals to the brain.
—Aria Bendix, NBC news, 20 Feb. 2026
The groups are called molecules.
—Reader Commentary, Baltimore Sun, 20 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 25 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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