1. pertaining to a coincidence of tides.
  2. (on a chart or map) indicating a line connecting points at which high tide occurs at the same time.

Origin of cotidal

First recorded in 1825–35; co- + tidal Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for cotidal


  1. (of a line on a tidal chart) joining points at which high tide occurs simultaneously
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

cotidal in Science


  1. Indicating coincidence of high tides or low tides.
  2. Relating to a line that passes through each location on a coastal map where tides occur at the same time of day. Cotidal maps show variation in the height of the tides and indicate the time of high tide occurrence. Cotidal charts can be made using tide gauge data from gauges at regular intervals along the coast; however, computer modeling is increasingly used, especially where the tides vary greatly over a short distance.
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