n.1 the third season of the year, when crops and fruits are gathered, and leaves fall, in the N. hemisphere from September to November and in the S. hemisphere from March to May.
2 Astron. the period from the autumnal equinox to the winter solstice.
3 a time of maturity or incipient decay.
Phrases and idioms:
autumn crocus any plant of the genus Colchicum, esp. meadow saffron, of the lily family and unrelated to the true crocus.
Etymology: ME f. OF autompne f. L autumnus