/ Dictionary / Index P phthalein: Meaning and Definition of Find definitions for: phthal•ein Pronunciation: (thal'ēn, -ē-in, fthal'-), [key] — n. Chem. any of a group of compounds formed by treating phthalic anhydride with phenols, from which certain important dyes are derived. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. PHS phthalic Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language