from The American Heritage® Dictionary of the English Language, 4th Edition
- 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.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. any of a range of lactones formed by the reaction of phenols with phthalic anhydride
from the GNU version of the Collaborative International Dictionary of English
- n. One of a series of artificial organic dyes made as condensation products of the phenols with phthalic acid, and well represented by phenol phthaleïn. Their alkaline solutions are fluorescent.
from The Century Dictionary and Cyclopedia
- n. One of the group of coloring-matters formed by the condensation of phthalic anhydrid with phenols. Some of the phthaleins have a purgative action when taken internally. They are of particular importance in the color-chemistry, and certain of their derivatives are valuable dyestuffs. See phenolphthalein and phthalic anhydrid.
phthal(ic) + -ein.(American Heritage® Dictionary of the English Language, Fourth Edition)