eosin
eo.sin or eo.sine \'e--*-s*n\ \-s*n, -.se-n\ n [ISV, fr. Gk e-o-s dawn] 1: a red fluorescent dye C20H8Br4O5 obtained by the action of bromine on fluorescein and used esp. in cosmetics and as a toner; also : its red to brown sodium or potassium salt used esp. in pink or red organic pigments 2: any of several dyes related to eosin