/ Dictionary / Index A alpha-naphthyl group: Meaning and Definition of Find definitions for: al'pha-naph'thyl group" Pronunciation: (al'fu-naf'thil, -nap'-, al"-), [key] — Chem. Chem. See(def. 1). Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. alpha-naphthol alpha-naphthylthiourea Related Content Daily Word Quiz: taut Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language