8 letters · 15 points in Scrabble
adjective not having or producing echoes; sound-absorbent
originFrom an- + echoic, from echo + -ic, from Middle English ecco, ekko, from Medieval Latin ecco, from Latin echo, from Ancient Greek ἠχώ (ēkhṓ), from ἠχή (ēkhḗ, “sound”).
Etymology from Wiktionary, CC BY-SA 3.0