What does autumn wind mean in the twenty-four solar terms?

Not the autumn wind, but the autumnal equinox. In the 24 solar terms, the autumnal equinox means that the climate changes from hot to cold. According to the division of seasons in ancient China, which began with beginning of spring, Changxia, beginning of autumn and beginning of winter, the autumnal equinox falls within 90 days of autumn and is divided equally in autumn.

In ancient times, the dichotomy (vernal equinox, autumnal equinox, summer solstice and winter solstice), as an important solar term, has always been valued by rulers. As early as the Zhou Dynasty, there was a custom of "offering sacrifices to the sun at the vernal equinox, to the ground at the summer solstice, to the moon at the autumnal equinox, and to heaven at the winter solstice". Today's well-known Mid-Autumn Festival is actually developed from the Mid-Autumn Festival at the autumnal equinox.

In addition to offering sacrifices to the moon, in ancient rural society, an autumn club was set up on the day of the autumn equinox to offer sacrifices to the land gods. Autumn Festival is an important activity in traditional rural society, and its scale is even bigger than Spring Festival.