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

However, making a molecule rotate predictably under an electric current while maintaining electrical contact with metal electrodes has remained a challenge. — Rupendra Brahambhatt, Interesting Engineering, 24 Oct. 2026

Anemia is often caused by a lack of iron, which supports brain and muscle function and is used to make hemoglobin, the molecule that transports oxygen in the blood. — Amanda Schupak, CNN Money, 23 Oct. 2026

Nature, over four billion years of evolutionary history, has learned to build some remarkable molecules. — Literary Hub, 23 Oct. 2026

Min and 11 colleagues, including researchers from the University of California Berkeley and Rutgers University, found water molecules behave differently when coming into contact with microplastics. — Michael Hawthorne, Chicago Tribune, 22 Oct. 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