万年

1. Origins, structure, and basic meaning

• Structure: 万年, read まんねん, literally means ten thousand years and can also express an extremely long duration.
• Basic usage: It gives a legendary tree an immense lifespan and forms 万年雪, snow that persists even through summer.

2. Common pitfalls and similar expressions

• Ten thousand years and extremely long duration
  • It gives the literal span of ten thousand years in a story and expresses very long persistence in the compound for snow that remains through summer.