noun which may take the genitive case particle 'no', noun
long-standing; long-cherished; of many years
Used as a pre-nominal modifier (～の) to describe something that has existed or been felt for many years, such as a wish, problem, or relationship.
年来の夢がついに叶った。
My long-cherished dream has finally come true.
これは年来の懸案事項だ。
This is a long-standing pending issue.
adverb
for years; over the years; for a long time
Adverbial use indicating that something has continued or been done over a period of years up to the present.
彼は年来この町に住んでいる。
He has been living in this town for years.
年来の研究が実を結んだ。
Years of research have borne fruit.