equinoctial tide; equinoctial spring tide
A tide occurring around the equinoxes, often with a larger range than usual. Used in nautical and geographical contexts.
During the equinoctial tide period, the difference between high and low tide becomes large.
Compound of 彼岸 (higan, 'equinoctial week') and 潮 (shio, 'tide'), referring to the tides around the spring and autumn equinoxes.