Xanthene Dye Definition

Any of various dyes that contain the xanthene ring structure in their molecules.
Webster's New World

Any of a group of brilliant fluorescent yellow to pink to bluish red dyes characterized by the presence of the xanthene nucleus, known sometimes in colorless as well as colored forms, and used chiefly in dyeing textile fibers, in coloring paper, in producing fluorescent effects, and as organic pigments.