名詞 phenolphthalein:

1. 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

phe.nol.phthal.ein

n.（名詞）
A white or pale yellow crystalline powder, C20H 4O 4, used as an acid-base indicator, in making dyes, and in medicine as a laxative.
苯酚酞：一種白色或淡黃色的晶體粉末，C20H 4O 4，用作酸性指示劑，用于制染料，并在醫(yī)學(xué)上用作一種輕瀉劑