the season between summer and winter; fall. In the Northern Hemisphere it is from the September equinox to the December solstice; in the Southern Hemisphere it is from the March equinox to the June solstice.

a time of full maturity, esp. the late stages of full maturity or, sometimes, the early stages of decline

to be in the autumn of one's life.

noun

spring

noun

autumnal equinox , fall , harvest , indian summer , season