Definition of "eosin" [e•o•sin]

• A red crystalline powder, C20H8O5Br4, used in textile dyeing and ink manufacturing and in coloring gasoline. (noun)
• The red sodium or potassium salt of this powder, used in biology to stain cells. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The protoplasm is clear, and contains a number of very fine granules, which stain with acid dyes, such as eosin, or with neutral dyes, and are therefore called oxyphil or neutrophil (Fig. 454, P)."
• "Stained tissue culture cells and thin sections were labeled with either fluorescent dyes or common histology stains such as eosin, fast green, and safranin."
• "His contributions include, in particular, structure determination of organic dyes (indigo, eosin) and the study of aromatic compounds (terpenes)."