noun
perpetual snow; firn
Refers to snow that persists year-round in high mountains or polar regions, often compacted into firn. Used in geography and mountaineering contexts.
この山の頂上付近には万年雪が残っている。
Perpetual snow remains near the summit of this mountain.
Compound of 万年 (man'nen, 'ten thousand years, eternity') and 雪 (yuki, 'snow'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning of snow that lasts for many years.