Etymograph

English

thermos

Thermos comes from Ancient Greek θερμός ‘warm’, and goes back to Proto-Indo-European *gʷʰer-.

  1. Proto-Indo-Europeanc. 4500–2500 BCE*gʷʰer-1‘to be warm’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*gʷʰermos1reconstructed
  3. Proto-Hellenicc. 2200–1600 BCE*kʷʰermós1reconstructed
  4. Ancient Greekc. 800–300 BCEθερμός2thermós‘warm’
  5. Englishtodaythermos2

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, Ancient Greek θερμός
  2. 2 Wiktionary, English thermos

Lineage

  1. Proto-Indo-Europeanc. 4500–2500 BCE*gʷʰer-Wiktionary, Ancient Greek θερμός‘to be warm’reconstructed
  2. Proto-Indo-Europeanc. 4500–2500 BCE*gʷʰermosWiktionary, Ancient Greek θερμόςreconstructed
  3. Proto-Hellenicc. 2200–1600 BCE*kʷʰermósWiktionary, Ancient Greek θερμόςreconstructed
  4. Ancient Greekc. 800–300 BCEθερμόςWiktionary, English thermosthermós‘warm’
  5. EnglishtodaythermosWiktionary, English thermos

The story

Possibly related to English warm.

Full etymology on Wiktionary

Linked words

through Proto-Indo-European *gʷʰer- ‘to be warm’

warm, gore, furnace, gory, forceps, garlick, 19 more

Another origin of thermos

  1. Ancient Greekc. 800–300 BCEθέρμος
  2. Englishtodaythermos

Today it means

noun A bottle, flask or similar vessel having a vacuum between its inner and outer silvered walls; designed to maintain the temperature of its contents

Sources

Sources: Wiktionary, “thermos”; the older steps come from the Wiktionary entry for Ancient Greek θερμός. 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 *gʷʰer- / thermos

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