1. The third season of the year, astronomically, beginning at the equinox, when the sun enters libra, and ending at the winter solstice; but popularly comprising September, October, and November; a period of decay.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• butumen,
• autam,
• authumn,
• autunm,
• automn,
• autium,
• autmn,
• automen,
• aurtum,
• auton,
• autumm,
• autums,
• annumn,
• aotumn,
• autunn,
• autsin,
• autume,
• autom,
• automy,
• auttumn

• AUTON,
• autin,
• Auten,
• auden.

The adjective form of the word "autumn" is "autumnal".

The plural of the "autumn" can be the "autumns".

The singular of the "autumn" can be the "autumn".