The season of the year between summer and winter, lasting from the autumnal equinox to the winter solstice and from September to December in the Northern Hemisphere; fall.
A period of maturity verging on decline.
adj.
Of, having to do with, occurring in, or appropriate to the season of autumn: autumn foliage; autumn harvests.
Grown during the season of autumn: autumn crops.
[Middle English autumpne, from Old French autompne, from Latin autumnus.] au·tum'nal (ô-tŭm'nəl) adj., au·tum'nal·ly adv.