Cotidal \Co*tid"al\ (k?-t?d"al), a. Marking an equality in the tides; having high tide at the same time. [1913 Webster]

Cotidal lines (Phys. Geog.), lines on a map passing through places that have high tide at the same time. [1913 Webster] Cotillon

Source: The Collaborative International Dictionary of English v.0.48
 

Cotidal \Co*tid"al\ (k?-t?d"al), a. 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.

Source: Webster's Revised Unabridged Dictionary (1913)