13 letters · 21 points in Scrabble
noun the lower layer of the crust
originEtymology tree English astheno- Ancient Greek σφαῖρᾰ (sphaîră)bor. Latin sphaera Late Latin sphērader. Old French spherebor. Middle English spere English sphere English -sphere English asthenosphere From astheno- + -sphere.
Etymology from Wiktionary, CC BY-SA 3.0