phenolphthalin
/ˌfiːnɒlˈ(f)θeɪlɪn/ /ˌfiːnɒlˈ(f)θalɪn/Chemistry
noun
A crystalline solid, (C6H4OH)2CHC6H5COOH, which gives phenolphthalein when oxidized, and is used as an indicator.
Origin
Late 19th century; earliest use found in Journal of the Chemical Society. From phenol + phthalin.