equinox
CEFR: C1
Either of the two times each year (vernal in March and autumnal in September) when the sun crosses the celestial equator and day and night are of equal duration worldwide.
Common Collocations
- autumn equinox
- spring equinox
- vernal equinox
Example Sentence
Ancient megalithic monuments were engineered with solar alignments to mark the spring and autumn equinox.