The season between summer and winter. It lasts from the autumnal equinox to the winter solstice.

The season of the year that is the transition period from summer to winter, occurring as the sun approaches the winter solstice.

The season of the year which occurs as the sun approaches the winter solstice, and characterized by decreasing temperatures in the mid-latitudes. Customarily, this refers to the months of September, October, and November in the North Hemisphere and the months of March, April, and May in the Southern Hemisphere. Astronomically, this is the period between the autumnal equinox and the winter solstice.

Autumn (also known as fall in North American English) is one of the four temperate seasons, the transition from summer into winter. In the temperate zones, autumn is the season during which most crops are harvested, and deciduous trees lose their leaves. It is also the season where days rapidly get shorter and cooler, the nights rapidly get longer, and of gradually increasing precipitation in some parts of the world.