山岳
さんがく · sangaku · JLPT N1 · noun
mountain
⛰ 山 (mountain) + 岳 (high peak) = sangaku: mountain + peak, meaning a range of mountains
Both characters mean mountain. 岳 specifically names a tall, steep peak, so doubling up the idea gives the plural sense of many mountains together.
山 — pictograph of three mountain peaks
山 is one of the oldest pictographs in Chinese, originally drawn in oracle bone script as three pointed peaks rising from a baseline. The form was simplified over time into the modern three vertical strokes on a base. Its meaning has stayed remarkably stable: 'mountain' or 'hill'.