When should I say 10年越しの夢 instead of 10年の夢?


10年越しの夢がようやく叶った。

10年の夢がようやく叶った。

I'm familiar with using the particle の before a noun to form an adjective-like
possessive form. But how is 越しの different from saying の?

[What does 鏡越し mean in this
sentence?](https://japanese.stackexchange.com/questions/41283/what-
does-%E9%8F%A1%E8%B6%8A%E3%81%97-mean-in-this-sentence)

I read this past question, but it still does not solve my question.




「10年{ねん}の夢{ゆめ}」, while it is something native speakers would actually say,
sounds quite plain. It sounds as though 10 years were not such a long time to
wait for the dream to come true.

In order to emphasize just how long the 10-year period has felt to the
speaker/writer, we would often say:

「10年[越]{ご}しの夢」 or

「10年[来]{らい}の夢」

Both would be very useful expressions to learn.

