phenolphthaleinPronunciation: /ˌfiːnɒlˈ(f)θaliːn, -ˈ(f)θeɪl-/Definition of phenolphthalein noun [mass noun] Chemistry a colourless crystalline solid (pink in alkaline solution) used as an acid-base indicator and medicinally as a laxative. Chemical formula: C20H14O4 Origin: late 19th century: from phenol + -phthal- (from naphthalene) + -in1phenolphthalein in other Oxford dictionaries Definition of phenolphthalein in the US English dictionary
