[ mol-uh-kyool ]
See synonyms for: moleculemolecules on

  1. 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.

  2. Chemistry. a quantity of a substance, the weight of which, measured in any chosen unit, is numerically equal to the molecular weight; gram molecule.

  1. any very small particle.

Compare Meanings

Click for a side-by-side comparison of meanings. Use the word comparison feature to learn the differences between similar and commonly confused words.

Origin of molecule

First recorded in 1785–95; earlier molecula, from New Latin, from Latin mōlē(s) “mass” (cf. molar2 ) + -cula -cule1

Other words from molecule

  • sub·mol·e·cule, noun
  • su·per·mol·e·cule, noun

Words Nearby molecule Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use molecule in a sentence

British Dictionary definitions for molecule


/ (ˈmɒlɪˌkjuːl) /

  1. the simplest unit of a chemical compound that can exist, consisting of two or more atoms held together by chemical bonds

  2. a very small particle

Origin of molecule

C18: via French from New Latin mōlēcula, diminutive of Latin mōlēs mass, mole 4

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for molecule


[ mŏlĭ-kyōōl′ ]

  1. A group of two or more atoms linked together by sharing electrons in a chemical bond. Molecules are the fundamental components of chemical compounds and are the smallest part of a compound that can participate in a chemical reaction.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for molecule


[ (mol-uh-kyoohl) ]

A combination of two or more atoms held together by a force between them. (See covalent bond and ionic bond.)

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.