Standard Lemma guide

fluorescein

noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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1

noun

Meaning 1

Any of a class of yellow xanthene dyes which are visible when highly diluted; used forensically to detect traces of blood, and in analytical chemistry as an indicator in silver nitrate titrations

Definition source: English Wiktionary via Wiktextract

Topics: chemistry, natural-sciences, organic-chemistry, physical-sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: resorcinolphthalein

Antonyms: none provided

2

noun

Meaning 2

a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution and negative fluorescein ions are then absorbed)

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: fluoresceine, fluorescent dye, resorcinolphthalein

Antonyms: none provided

Broader terms: absorption indicator, dye, dyestuff

Narrower terms: eosin, bromeosin

History

Etymology

Etymology tree Proto-Indo-European *bhel-der. Proto-Indo-European *bhlewH-der. Proto-Indo-European *bhluH-yé-ti? Latin fluō Proto-Indo-European *-os Proto-Indo-European *-s Proto-Indo-European *-ōs Proto-Italic *-ōs Latin -or Latin fluorbor. English fluor Proto-Indo-European *-tósder. Ancient Greek -της (-tēs)der. Ancient Greek -ῑ́της (-ī́tēs)der. Latin -ītēsbor. French -iteder. English -ite English fluorite Middle Low German sparder. Old English spærstān Middle English sparston English sparstonebf. English spar blend English fluorspar Proto-Indo-European *-éh1ti Proto-Indo-European *-sḱéti Proto-Indo-European *-éh1sḱeti Proto-Italic *-ēskō Latin -ēscō Latin -escensder. English -escence English fluorescencebf. English fluoresce Proto-Indo-European *-nós Proto-Indo-European *-iHnos Proto-Italic *-īnos Latin -īnusder. Old French -inbor. Middle English -in English -ineclip. English -in English fluorescein From fluoresce + -in.

Across languages

Translations

7 source translations are retained for this English entry.

  • Catalan: fluoresceïna — any of a class of yellow xanthene dyes which are visible when highly diluted
  • French: fluorescéine — any of a class of yellow xanthene dyes which are visible when highly diluted
  • German: Fluorescein — any of a class of yellow xanthene dyes which are visible when highly diluted
  • Hungarian: fluoreszcein — any of a class of yellow xanthene dyes which are visible when highly diluted
  • Italian: fluoresceina — any of a class of yellow xanthene dyes which are visible when highly diluted
  • Romanian: fluoresceină — any of a class of yellow xanthene dyes which are visible when highly diluted
  • Spanish: fluoresceína — any of a class of yellow xanthene dyes which are visible when highly diluted