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 quantum engineering of new molecules could lead to better drugs and to batteries that don’t use costly, environmentally damaging commodities such as rare earth elements.
—
Zeeya Merali, Scientific American, 19 May 2026
The AIs weren’t being asked to design entirely new molecules, and most drugs fail during the animal and clinical trials phase, rather than during testing in cell culture.
—ArsTechnica, 19 May 2026
B complex vitamins are vital for energy metabolism, supporting immune health, maintaining proper brain function, enabling DNA synthesis and repair, and facilitating the production of neurochemicals and signaling molecules.
—Lana Barhum, Verywell Health, 18 May 2026
Fledgling startups and pharmaceutical giants alike are addicted to Chinese drugs, spending some $60 billion on Chinese molecules in the first three months of 2026 alone.
—O. Rose Broderick, STAT, 18 May 2026
See All Example Sentences for molecule
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Zeeya Merali, Scientific American, 19 May 2026
The AIs weren’t being asked to design entirely new molecules, and most drugs fail during the animal and clinical trials phase, rather than during testing in cell culture.
—ArsTechnica, 19 May 2026
B complex vitamins are vital for energy metabolism, supporting immune health, maintaining proper brain function, enabling DNA synthesis and repair, and facilitating the production of neurochemicals and signaling molecules.
—Lana Barhum, Verywell Health, 18 May 2026
Fledgling startups and pharmaceutical giants alike are addicted to Chinese drugs, spending some $60 billion on Chinese molecules in the first three months of 2026 alone.
—O. Rose Broderick, STAT, 18 May 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 20 May. 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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