Phthalein \Phthal"e*in\, n. [See {Phthalic}.] (Chem.)
One of a series of artificial organic dyes made as
condensation products of the phenols with phthalic acid, and
well represented by phenolphthalein. Their alkaline solutions
are fluorescent.
[1913 Webster]
{Phenol phthalein}, a white or yellowish white crystalline
substance made from phthalic acid and phenol. Same as
{phenolphthalein}.
[1913 Webster + PJC]