• (n.) A red or violet dyestuff having a greenish metallic luster. It is produced artificially, by the chemical dehydration of thionine, as a brown amorphous powder.
Thi'on·ol noun [ Thion ine + - ol .] (Chemistry) A red or violet dyestuff having a greenish metallic luster. It is produced artificially, by the chemical dehydration of thionine, as a brown amorphous powder.