10 letters · 22 points in Scrabble
adjective (of a chemical reaction or compound) occurring or formed with the liberation of heat
originEtymology tree Proto-Indo-European *h₁éǵʰ Proto-Indo-European *-s Proto-Indo-European *h₁eǵʰs Proto-Hellenic *eks Ancient Greek ἐκ (ek) Ancient Greek ἔξω (éxō)der. English exo- English thermal English exothermal From exo- + thermal.
Etymology from Wiktionary, CC BY-SA 3.0