What is another word for autumnal equinox?

It depends which autumnal equinox you mean. In the sense “September 22”, the synonyms are September equinox, fall equinox. Across all 2 senses there are 2 distinct synonyms, and they are not interchangeable with each other — this page lists them under the sense each one belongs to.

What is the opposite of autumnal equinox?

The recorded antonym is vernal equinox. Opposites are sense-specific too: this page shows which meaning each one is the opposite of, because a word rarely has a single opposite that holds for all of its senses.

Why are the synonyms for autumnal equinox split into groups?

Because autumnal equinox carries 2 recorded senses and each has its own set of substitutes. A single flat list would put words from unrelated meanings side by side with nothing to tell them apart, which is exactly how a writer picks the wrong one. The grouping comes from WordNet's synsets, not from an editorial judgement of ours.

Where do the synonyms for autumnal equinox come from?

From Princeton University's WordNet, a lexical database maintained by lexicographers since 1985. A synonym here means a word form that shares a synset with this word — a set of forms interchangeable in one recorded context. Nothing on this page is generated by a language model.

Synonyms and antonyms

autumnal equinox

nounRare

autumnal equinox has 2 distinct synonyms spread across 1 of its 2 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is vernal equinox.

2
Distinct synonyms: 1
Antonym: 2 of 2
Senses with a relation

Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.