eosin

e·o·sin   (ē'ə-sən)    n.   A red crystalline powder, C20H8O5Br4, used in textile dyeing and ink manufacturing and in coloring gasoline. The red sodium or potassium salt of this powder, used in biology to stain cells. [Greek ēōs, dawn (from its color); see aus- in Indo-European roots + -in.]

Main Entry: eo·sin
Pronunciation: 'E-&-s&n
Variant: also eo·sine /-s&n, -"sEn/
Function: noun
1 : a red fluorescent dye C₂₀H₈Br₄0₅ obtained by the action of bromine on fluorescein and used especially in cosmetics and as a toner; also : its red to brown sodium or potassium salt used especially as a biological stain for cytoplasmic structures
2 : any of several dyes related to eosin

eosin e·o·sin (ē'ə-sən)
n.
Any of a class of red acid dyes of the xanthene group used as cytoplasmic stains and as counterstains, especially the sodium and potassium salts of certain of these dyes.