phenolphthalein

UK: /ˌfiːnɒlˈθeɪliːn/

US: (fē′nôl thal′ēn, -ē in, -fthal′-, -nol-)

WordReference Random House Unabridged Dictionary of American English © 2025

phe•nol•phthal•ein  (fē′nôl thal′ēn, -ē in, -fthal′-, -nol-), n. [Chem., Pharm.]

1. Chemistry, Drugs a white, crystalline compound, C₂₀H₁₄O₄, used as an indicator in acid-base titration and as a laxative.

• phenol + phthalein 1870–75

Collins Concise English Dictionary © HarperCollins Publishers::

phenolphthalein / ˌfiːnɒlˈθeɪliːn -lɪɪn -ˈθæl-/ noun

1. a colourless crystalline compound used in medicine as a laxative and in chemistry as an indicator. Formula: C₂₀H₁₄O₄