Etymograph

English

caesium

Caesium comes from Latin caesius ‘sky-blue’, from caedō ‘I cut’, and ultimately from Proto-Indo-European *kh₂eyd-.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*kh₂eyd-1‘to cut, hew’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*kh₂éydeti1reconstructed
  3. Proto-Italicc. 1500–700 BCE*kaidō1‘to cut, hew, fell’reconstructed
  4. Latinc. 75 BCE–200 CEcaedō2‘I cut’
  5. Latinc. 75 BCE–200 CEcaesius3‘sky-blue’
  6. Englishtodaycaesium3

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Latin caedo
  2. 2 Wiktionary, Latin caesius
  3. 3 Wiktionary, English caesium

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*kh₂eyd-Wiktionary, Latin caedo‘to cut, hew’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*kh₂éydetiWiktionary, Latin caedoreconstructed
  3. Proto-Italicc. 1500–700 BCE*kaidōWiktionary, Latin caedo‘to cut, hew, fell’reconstructed
  4. Latinc. 75 BCE–200 CEcaedōWiktionary, Latin caesius‘I cut’
  5. Latinc. 75 BCE–200 CEcaesiusWiktionary, English caesium‘sky-blue’
  6. EnglishtodaycaesiumWiktionary, English caesium

Linked words

through Proto-Indo-European *kh₂eyd- ‘to cut, hew’

hit, 26 more

through Proto-Italic *kaidō ‘to cut, hew, fell’

scissors, 24 more

through Latin caedō ‘I cut’

decision, precise, cement, concise, incision, chisel, scissor, circumcision, incisive, excision, incisor, 25 more

Today it means

noun The chemical element (symbol Cs) with an atomic number of 55. It is a soft, gold-colored, highly reactive alkali metal.

Sources

Sources: Wiktionary, “caesium”; the older steps come from the Wiktionary entries for Latin caedo, Latin caesius. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Proto-Indo-European *kh₂eyd- / caesium

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