noun
mountain trail; path up a mountain
Refers to a designated hiking trail or path on a mountain, often maintained for climbers.
この登山道は初心者でも歩きやすい。
This mountain trail is easy to walk even for beginners.
登山道が雨でぬかるんでいた。
The mountain path was muddy from the rain.
山道 is a broader term for any mountain road or path, not necessarily a maintained hiking trail.
Compound of 登山 (tozan, 'mountain climbing') and 道 (dō, 'road, path').