[naf-thuh-leen, nap-]

noun Chemistry.

a white, crystalline, water-insoluble hydrocarbon, C10H8, usually obtained from coal tar: used in making dyes, as a moth repellant, etc.

Also naph·tha·line, naph·tha·lin [naf-thuh-lin, nap-] /ˈnæf θə lɪn, ˈnæp-/.

Origin of naphthalene

First recorded in 1865–70; naphth- + -al3 + -ene
Also called tar camphor.
Related formsnaph·thal·ic [naf-thal-ik, nap-] /næfˈθæl ɪk, næp-/, naph·tha·len·ic [naf-thuh-len-ik, nap-] /ˌnæf θəˈlɛn ɪk, ˌnæp-/, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for naphthalene

Historical Examples of naphthalene

  • As aniline is to benzene, so are the naphthylamines to naphthalene.


    Raphael Meldola

  • The important constituents of this portion are carbolic acid and naphthalene.


    Raphael Meldola

  • The story of naphthalene is summarized in the schemes on pp. 164, 165.


    Raphael Meldola

  • It is possible to start from benzene, toluene or naphthalene.

    Creative Chemistry

    Edwin E. Slosson

  • An excess of naphthalene should also be avoided, since, on account of its strong odour, soaps containing much of it are unpopular.

British Dictionary definitions for naphthalene


naphthaline naphthalin (ˈnæfθəlɪn, ˈnæp-)


a white crystalline volatile solid with a characteristic penetrating odour: an aromatic hydrocarbon used in mothballs and in the manufacture of dyes, explosives, etc. Formula: C 10 H 8
Derived Formsnaphthalic (næfˈθælɪk, næp-), adjective

Word Origin for naphthalene

C19: from naphtha + alcohol + -ene
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

Word Origin and History for naphthalene

1821, coined by English chemist John Kidd (1775-1851), who first isolated and studied it, from naphtha + chemical suffix -ine (2) + -l- for the sake of euphony.

Online Etymology Dictionary, © 2010 Douglas Harper

naphthalene in Medicine



A toxic carcinogenic hydrocarbon derived from coal tar or petroleum and used as a solvent.
Related formsnaph′tha•lenic (-lĕnĭk) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

naphthalene in Science



A white crystalline compound made from coal tar or petroleum and used to make dyes, mothballs, explosives, and solvents. Naphthalene consists of two benzene rings fused together. Chemical formula: C10H8.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.