phthalein

[thal-een, -ee-in, fthal-] /ˈθæl in, -i ɪn, ˈfθæl-/
noun, Chemistry
1.
any of a group of compounds formed by treating phthalic anhydride with phenols, from which certain important dyes are derived.
Origin
1900-05; (na)phthale(ne) + -in2
British Dictionary definitions for phthalein

phthalein

/ˈθeɪliːn; -lɪɪn; ˈθæl-; ˈfθæl-/
noun
1.
any of a class of organic compounds obtained by the reaction of phthalic anhydride with a phenol and used in dyes
Word Origin
C19: from phthal-, shortened form of naphthalene +-in
phthalein in Medicine

phthalein phthal·ein or phthal·eine (thāl'ēn', thāl'ē-ĭn, thā'lēn', thā'lē-ĭn)
n.
Any of a group of chemical compounds formed by a reaction of phthalic anhydride with a phenol, from which certain synthetic dyes are derived.

phthalein in Science
phthalein
  (thāl'ēn', thā'lēn', fthāl'-)   
Any of a group of chemical compounds formed by a reaction of phthalic anhydride with a phenol. They are used to derive certain synthetic dyes.