Etymology

thermosphere

T1H4E1R1M3O1S1P3H4E1R1E1

Today it means: The layer of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Full definition →

English sphere ← Middle English spere ← Old French sphere
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The story

  1. Proto-Indo-European*gʷʰer-
  2. Proto-Indo-European*gʷʰermos
  3. Proto-Hellenic*kʷʰermós
  4. Ancient Greekθερμός (thermós)
  5. Englishthermo-
  6. Ancient Greekσφαῖρᾰ (sphaîră)
  7. Latinsphaera
  8. Late Latinsphēra
  9. Old Frenchsphere
  10. Middle Englishspere
  11. Englishsphere
  12. English todaythermosphere

From thermo- + -sphere.

Etymology from Wiktionary, CC BY-SA 4.0.