noun
great mountain; large mountain
A learned or elevated noun for a very large, imposing mountain. In everyday speech, 大きな山 is usually more natural; 大山 often appears in literary phrasing, set expressions, or figurative comparisons.
目の前に大山がそびえていた。
A great mountain towered before us.
「大山鳴動して鼠一匹」とは
The saying “a great mountain rumbles and only one mouse appears” means that a huge fuss produces only a tiny result.