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

a molecule of political honesty

—Time

Synonyms

• atom
• bit
• crumb
• dribble
• fleck
• flyspeck
• grain
• granule
• morsel
• mote
• nubbin
• nugget
• particle
• patch
• scrap
• scruple
• snip
• snippet
• speck
• tittle

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 researchers behind the brain plastics study think the tiny shards of plastic hitch a ride on fat molecules to get inside brain cells. —Megha Satyanarayana, Scientific American, 14 Feb. 2025

Life’s Building Blocks Inside an Asteroid: Scientists studying samples that NASA collected from the asteroid Bennu found a wide assortment of organic molecules that shed light on how life arose. —Jason Bittel, New York Times, 12 Feb. 2025

Like how your left glove fits only your left hand and your right glove your right hand, chiral molecules can interact only with other molecules of compatible handedness. —Kate Adamala, The Conversation, 11 Feb. 2025

These molecules travel to the colon, where bacteria ferment them. —Merve Ceylan, Health, 11 Feb. 2025

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

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