• synonyms


noun Chemistry.
  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.
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Also e·o·sine [ee-uh-sin, -seen] /ˈi ə sɪn, -ˌsin/.

Origin of eosin

1865–70; < Greek ēṓs dawn (see eo-) + -in2
Related formse·o·sin·ic, adjectivee·o·sin·like, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for eosine

Historical Examples

  • The dyes with the ponceaus are faster than those with eosine or safranine.

    The Practical Ostrich Feather Dyer

    Alexander Paul

  • The eosine plate was underexposed, but brought up everything fairly well except the scarlet hat, which came up like black.

  • Very good results in soap may be obtained by mixing a fast blue, as ultramarine or cobalt blue, with a red as rhodamine or eosine.

    Soap-Making Manual

    E. G. Thomssen

  • In the latter mixture they stain really with the methylene blue salt of eosine.

  • Potassa turns rosolic acid and coralline from an orange-red to a bright red, while it produces no change in eosine.

British Dictionary definitions for eosine


eosine (ˈiːəʊsɪn, -ˌsiːn)

  1. Also called: bromeosin a red crystalline water-insoluble derivative of fluorescein. Its soluble salts are used as dyes. Formula: C 20 H 8 Br 4 O 5
  2. any of several similar dyes
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Derived Formseosinic, adjectiveeosin-like, adjective

Word Origin

C19: from Greek ēōs dawn + -in; referring to the colour it gives to silk
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

eosine in Medicine


  1. 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.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.