e·qui·noc·tial 
(ē′kwə-nŏkshəl, ĕk′wə-)
(ē′kwə-nŏkshəl, ĕk′wə-)adj.
1. Relating to an equinox.
2. Relating to the celestial equator.
n.
1. A violent storm of wind and rain occurring at or near the time of the equinox.
2. See celestial equator.
[Middle English equinoxial, from Old French, from Latin aequinoctiālis, from aequinoctium, equinox; see EQUINOX.]