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
In addition, the peptide seems to promote angiogenesis, the development of new blood vessels, possibly via a signalling molecule expressed in many human cancers.
—
Dhruv Khullar, New Yorker, 6 Apr. 2026
Research shows the area releases millions of particles, aerosols and molecules of dangerous pollutants into the air — including hydrogen sulfide, which has twice spiked to record levels in the last two weeks, according to data from the San Diego County Air Pollution Control District.
—Walker Armstrong, San Diego Union-Tribune, 5 Apr. 2026
The process causes a violent compression of air molecules that can heat the spacecraft’s exterior to more than 5,000 degrees Fahrenheit (2,760 degrees Celsius).
—Jackie Wattles, CNN Money, 3 Apr. 2026
In muscle cells myosin molecules assemble into thick filaments through interactions among their tail regions.
—Encyclopedia Britannica, 3 Apr. 2026
See All Example Sentences for molecule
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Dhruv Khullar, New Yorker, 6 Apr. 2026
Research shows the area releases millions of particles, aerosols and molecules of dangerous pollutants into the air — including hydrogen sulfide, which has twice spiked to record levels in the last two weeks, according to data from the San Diego County Air Pollution Control District.
—Walker Armstrong, San Diego Union-Tribune, 5 Apr. 2026
The process causes a violent compression of air molecules that can heat the spacecraft’s exterior to more than 5,000 degrees Fahrenheit (2,760 degrees Celsius).
—Jackie Wattles, CNN Money, 3 Apr. 2026
In muscle cells myosin molecules assemble into thick filaments through interactions among their tail regions.
—Encyclopedia Britannica, 3 Apr. 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 7 Apr. 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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