- 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, especially the late stages of full maturity or, sometimes, the early stages of decline: to be in the autumn of one's life.
- (sometimes capital)
- the season of the year between summer and winter, astronomically from the September equinox to the December solstice in the N hemisphere and from the March equinox to the June solstice in the S hemisphere
- (as modifier)
- a period of late maturity, esp one followed by a decline
