ˈthalēə̇n, -āl-, -ˌlēn noun
also phthalein dye
( -s )
Etymology: International Scientific Vocabulary phthal- + -ein
: any of a group of xanthene dyes (as phenolphthalein, fluorescein, rhodamine) that are intensely colored in alkaline solution and are obtained by condensation of phenols with phthalic anhydride