/ Dictionary / Index N naphthol: Meaning and Definition of Find definitions for: naph•thol Pronunciation: (naf'thôl, -thol, nap'-), [key] — n. Chem. either of two isomeric hydroxyl derivatives, CHOH, of naphthaleneorandorwhite or yellowish crystals, with a phenolic odor, that darken on exposure to light: used chiefly in dyes, drugs, perfumes, and insecticides. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: naphthol (Thesaurus) naphthene naphthyl Related Content Daily Word Quiz: banshee Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language