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 key to their breakthrough was a molecule called trihydrogen cation (H₃⁺).
—
Rupendra Brahambhatt, Interesting Engineering, 28 Mar. 2026
To prevent the genetic material from disassembling too quickly, vaccine developers enclose the mRNA in a specialized mix of tiny fatty molecules called lipid nanoparticles.
—Meghan Bartels, Scientific American, 27 Mar. 2026
The first is flowers, the second a molecule, lignin.
—David George Haskell, Big Think, 27 Mar. 2026
During a recent presentation at the Medicine and Science in Ultra-Endurance Sports conference, Stuempfle cited endotoximea—when molecules normally confined to the GI tract leak into the blood—as a likely cause of severe stomach problems.
—Brad Stulberg, Outside, 26 Mar. 2026
See All Example Sentences for molecule
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Rupendra Brahambhatt, Interesting Engineering, 28 Mar. 2026
To prevent the genetic material from disassembling too quickly, vaccine developers enclose the mRNA in a specialized mix of tiny fatty molecules called lipid nanoparticles.
—Meghan Bartels, Scientific American, 27 Mar. 2026
The first is flowers, the second a molecule, lignin.
—David George Haskell, Big Think, 27 Mar. 2026
During a recent presentation at the Medicine and Science in Ultra-Endurance Sports conference, Stuempfle cited endotoximea—when molecules normally confined to the GI tract leak into the blood—as a likely cause of severe stomach problems.
—Brad Stulberg, Outside, 26 Mar. 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 31 Mar. 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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