molecule
Americannoun
-
Chemistry, Physics. the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound.
-
Chemistry. a quantity of a substance, the weight of which, measured in any chosen unit, is numerically equal to the molecular weight; gram molecule.
-
any very small particle.
noun
-
the simplest unit of a chemical compound that can exist, consisting of two or more atoms held together by chemical bonds
-
a very small particle
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of molecule
First recorded in 1785–95; earlier molecula, from New Latin, from Latin mōlē(s) “mass” ( cf. molar 2 ( def. )) + -cula -cule 1
Compare meaning
How does molecule compare to similar and commonly confused words? Explore the most common comparisons:
Explanation
A molecule is the simplest structural unit of a substance that still keeps the properties of that substance, like a molecule of water. This scientific word also gets used in unscientific ways, as in "Every single molecule in my body wants that chocolate cupcake!" People sometimes confuse molecules with atoms, but a molecule is made up of atoms. A molecule retains the characteristic of the substance it’s from, so a water molecule is still water. An atom only has the characteristics of its element, not the larger composition. For example, a water molecule, H2O, is made up of two hydrogen atoms and one oxygen atom.
Vocabulary lists containing molecule
Word Generation Science - Introductory Chemistry Concepts
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Words to Know Before You Defrost the Bird
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Cell Biology - Middle School
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Svensson has co-founded a company that plans to begin clinical trials of the molecule in humans in the near future.
From Science Daily ● Jul. 24, 2026
GLP-1 medications like Ozempic are also peptides: they mimic a naturally occurring molecule that regulates appetite, blood sugar and digestion.
From Barron's ● Jul. 23, 2026
Rather than reverse-engineering a large molecule, eCPs can hit the same biological target and produce the same clinical effect through a much simpler molecule.
From The Wall Street Journal ● Jul. 22, 2026
After two tick bites 50% of people will develop antibodies to alpha-gal, a sugar molecule found in the tick's saliva, van Nunen explains.
From BBC ● Jul. 20, 2026
To indicate the number of atoms in a molecule, Berzelius employed a superscript notation, as in H2O.
From "A Short History of Nearly Everything" by Bill Bryson
They are naturally occuring in the body, signaling molecules that dictate major physiological processes like tissue repair or metabolism.
From Barron's ● Jul. 23, 2026
So-called small molecules, which are typically pills dispensed by pharmacies, have generics that are much cheaper in the U.S. than abroad because of the intense price competition that patent expiration unleashes.
From The Wall Street Journal ● Jul. 22, 2026
"The discovery of the PS-TET mechanism has profound implications for many modern molecular technologies involving the spin-triplet excited states of molecules," Prof. Wu noted.
From Science Daily ● Jul. 22, 2026
That these molecules are easier to manufacture matters greatly for competition: Small molecules are the drugs for which generic price competition has already proved so beneficial to patients.
From The Wall Street Journal ● Jul. 22, 2026
Some are passed on to HLAs, special molecules that transport the snippets to the surface of the cell.
From "1491" by Charles C. Mann
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
