10 letters · 16 points in Scrabble
adjective of or relating to the heat in the interior of the earth
originEtymology tree Pre-Greek der. Proto-Hellenic *gayader. Ancient Greek γαῖᾰ (gaîă)clip. Ancient Greek γῆ (gê) Ancient Greek -ο- (-o-) Ancient Greek γεω- (geō-)der. English geo- English thermal English geothermal From geo- + thermal.
Etymology from Wiktionary, CC BY-SA 3.0