[al-fuh-naf-thawl, -thol, -nap-]

noun Chemistry.

See under naphthol.

Nearby words

  1. alpha-hydroxy acid,
  2. alpha-interferon,
  3. alpha-ketoglutaric acid,
  4. alpha-linolenic acid,
  5. alpha-lipoprotein,
  6. alpha-naphthyl group,
  7. alpha-naphthylthiourea,
  8. alpha-particle scattering,
  9. alpha-receptor,
  10. alpha-stannic acid


[naf-thawl, -thol, nap-]

noun Chemistry.

either of two isomeric hydroxyl derivatives, C10H7OH, of naphthalene (alpha-naphthol or 1-naphthol and beta-naphthol or 2-naphthol), white or yellowish crystals, with a phenolic odor, that darken on exposure to light: used chiefly in dyes, drugs, perfumes, and insecticides.

Origin of naphthol

First recorded in 1840–50; naphth- + -ol1

Also called hydroxynaphthalene. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for alpha-naphthol

  • Practically the only phenol that is used is the beta-naphthol; alpha-naphthol is occasionally used, but not often.

  • Alpha-naphthol for dark reds from Primuline, greys from Diamine blues, Neutral grey, etc.

British Dictionary definitions for alpha-naphthol



a white crystalline solid having two isomeric forms, alpha-naphthol, used in dyes, and beta-naphthol, used in dyes and as an antioxidant. Formula: C 10 H 7 OH

Word Origin for naphthol

C19: from naphtha + -ol 1

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

Medicine definitions for alpha-naphthol


[năfthôl′, -thōl′, năp-]


An organic compound occurring in two isomeric forms, alpha-naphthol and beta-naphthol.naphthalenol

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for alpha-naphthol


[năfthôl′, -thōl′, năp-]

A poisonous organic compound occurring in two isomeric forms. Both isomers are important in the manufacture of dyes, and also in making antiseptics, insecticides, and tanning agents. Naphthol consists of a hydroxyl group (OH) attached to naphthalene. Chemical formula: C10H8O.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.