autumnal equinox autumnal • autumnally · · · Info · Definitions · Synonyms · Antonyms · Characters · · autumnal equinox · · Text Common · · Latin · · Scripts 16 · · Length 8 · · Syllables Definitions · · · (noun) September 22. Synonyms: autumnal equinox, September equinox, fall equinox. · · Noun Definition 1 (noun) (astronomy) the equinoctial point that lies in the constellation of Virgo. Synonyms: autumnal equinox. · · Noun Definition 2 Synonyms · · · september equinox · · Synonym 1 fall equinox · · Synonym 2 Antonyms · · · vernal equinox · · Antonym 0 march equinox · · Antonym 1 spring equinox · · Antonym 2 Characters · · space U+0020 a latin small letter a U+0061 e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F q latin small letter q U+0071 t latin small letter t U+0074 u latin small letter u U+0075 x latin small letter x U+0078