noun
outer rim of a crater; somma
Geological term referring to the outer ridge of a volcanic crater or caldera.
阿蘇山の外輪山は世界最大級のカルデラの一部です。
The outer rim of Mount Aso is part of one of the world's largest calderas.
Compound of 外 (outside) + 輪 (ring) + 山 (mountain), describing the outer ring-shaped mountain ridge of a volcanic crater.