8 letters · 13 points in Scrabble
noun an electrically charged particle (electron or ion) emitted by a substance at a high temperature
originEtymology tree English therm- Proto-Indo-European *h₁ey- Proto-Indo-European *h₁éyti Proto-Hellenic *éimi Ancient Greek εἶμι (eîmi)der. English ion English thermion From therm- + ion.
Etymology from Wiktionary, CC BY-SA 3.0