phenolsulfonphthalein
noun
phe·nol·sul·fon·phtha·lein
variants:
or chiefly British phenolsulphonphthalein \ -ˌsəl-fän-ˈthal-ē-ən, -ˈthal-ˌēn, -ˈthāl- 
\
\
Medical Definition of phenolsulfonphthalein
: a red crystalline compound C19H14O5S used chiefly as a test of kidney function and as an acid-base indicator
— called also phenol red