1.
mid-autumn; the height of autumn
The middle of autumn — in the traditional lunar calendar, the 15th day of the 8th month, corresponding to September or early October in the Gregorian calendar. Strongly associated with moon viewing.
中 (middle) + 秋 (autumn). A largely literary or formal word; the everyday phrase for the season would be 秋の半ば.
Cultural note
中秋節 ('Mid-Autumn Festival') is observed across East Asia. In Japan, the 中秋の名月 (harvest moon) is the centerpiece of 月見 (moon viewing), traditionally celebrated with pampas grass (薄) and 月見団子 (round moon-viewing dumplings).