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Meaning of phthalein

phthal•ein

Pronunciation: (thal'ēn, -ē-in, fthal'-), [key]
— n. Chem.
  1. 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.