Noun: autumnal equinox o'túm-nul 'ee-kwu,nóks
- (astronomy) the equinoctial point that lies in the constellation of Virgo
"The autumnal equinox occurs around September 22nd each year"
- September 22
"The autumnal equinox marks the beginning of fall in the Northern Hemisphere";
- September equinox, fall equinox
Derived forms: autumnal equinoxes
Type of: equinoctial point, equinox
Part of: autumn, fall [N. Amer], Sep, Sept, September
Encyclopedia: Autumnal equinox