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
During this step, dopamine molecules self-assemble into an ultra-thin film.
—
Prabhat Ranjan Mishra, Interesting Engineering, 5 Jan. 2026
In the wild and in large numbers, all of those tiny molecules react with natural ozone molecules already in the air to form new particles and scatter blue light from the sun.
—Lisa Cericola, Southern Living, 2 Jan. 2026
By attacking a protein that is essential for replication, the molecule works against every influenza mutation, Stein explains.
—Noelle Harff, San Diego Union-Tribune, 31 Dec. 2025
Miller is taking another approach, studying a small molecule that targets a protein called nonmuscle myocin II.
—Stephanie Pappas, Scientific American, 30 Dec. 2025
See All Example Sentences for molecule
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Prabhat Ranjan Mishra, Interesting Engineering, 5 Jan. 2026
In the wild and in large numbers, all of those tiny molecules react with natural ozone molecules already in the air to form new particles and scatter blue light from the sun.
—Lisa Cericola, Southern Living, 2 Jan. 2026
By attacking a protein that is essential for replication, the molecule works against every influenza mutation, Stein explains.
—Noelle Harff, San Diego Union-Tribune, 31 Dec. 2025
Miller is taking another approach, studying a small molecule that targets a protein called nonmuscle myocin II.
—Stephanie Pappas, Scientific American, 30 Dec. 2025
See All Example Sentences for molecule
Cite this Entry
“Molecule.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/molecule. Accessed 11 Jan. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share