What is marking an equality in the tides; having high tide at the same time. Cotidal lines (Phys. Geog.), lines on a map passing through places that have high tide at the same time called?

cotidal — Marking an equality in the tides; having high tide at the same time. Cotidal lines (Phys. Geog.), lines on a map passing through places that have high tide at the same time. (Webster's 1913.)

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