Pronunciation: (ē'u-sin),[key] —n.Chem. 1. Also called bromeosin, tetrabromofluorescein. a red, crystalline, water-insoluble solid, C20H8Br4O5, derived from fluorescein by bromination: used chiefly as an acid dye for dyeing silk a rose red color and as a histological stain.
2. any of a variety of eosinlike dyes. Also,e•o•sinePronunciation: (ē'u-sin, -sēn").[key]