1. The great circles on the celestial sphere that pass through the celestial equator; also, the points where the sun crosses the celestial equator at the vernal and autumnal equinoxes.
Usage: astronomy; technical

1. Relating to or occurring at an equinox; happening when day and night are of equal length.
2. Relating to the equator or the region near the equator.
Usage: geography

Examples

• The equinoctials mark the moments when the sun is directly above the equator.
• Equinoctial storms are common during the spring and fall transitions.
• Astronomers use the equinoctials as reference points for celestial navigation.
• The equinoctial line divides the celestial sphere into northern and southern hemispheres.
• Ships sailing near the equinoctials often experience unpredictable weather patterns.
• The vernal equinoctial occurs around March 20 in the Northern Hemisphere.