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.

Synonyms of molecule

• particle
• speck
• atom
• bit
• patch
• fleck
• grain
• snippet
• scrap
• granule
• mouthful
• crumb
• shred

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

This means thinner air, which means fewer oxygen molecules are produced with each breath. — Adam Crafton, New York Times, 4 July 2026

Now imagine that same molecule, weeks later, traveling far beyond that moment of care. — Melissa Cristina Márquez, Forbes.com, 2 July 2026

Those animals have a specific sugar molecule in their blood called alpha-gal. — Erika Edwards, NBC news, 2 July 2026

For small, simple molecules, the researchers simply inserted a gene that encodes a pore protein into the SpudCell genome. — ArsTechnica, 2 July 2026

Word History

Etymology

French molécule, from New Latin molecula, diminutive of Latin moles mass

First Known Use

1701, in the meaning defined at sense 1

Rhymes for molecule

• minuscule
• overrule
• poiseuille
• reticule
• ridicule
• vestibule
• ampoule
• bascule
• carpool
• cesspool
• ferrule
• footstool

Kids 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