phenolphthalein phenoloid • phenolsulphonate · · · Info · Definitions · Characters · · phenolphthalein · · Text Latin · · Script 15 · · Length Definitions · · · (noun) a laxative used in many preparations under various trade names; also used as an acid-base indicator in titrations involving weak acids and strong bases because it is brilliant red at high alkalinity and colorless below pH 8. · · Noun Definition 1 Characters · · a latin small letter a U+0061 e latin small letter e U+0065 h latin small letter h U+0068 i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 t latin small letter t U+0074