noun
three autumn months; three years
Literary term. Can refer to the three months of autumn (by the lunar calendar) or, by extension, three years. The 'three years' meaning comes from the idea of three autumns passing. Rare in modern everyday speech; mostly found in classical poetry and literature.
漢詩に「三秋」という言葉が出てくる。
The word 'sanshū' appears in Chinese poetry.
「一日三秋」という成語は、一日が三年のように長く感じられることを表す。
The idiom 'ichijitsu sanshū' expresses that a single day feels as long as three years.