Cotidal is a term that is primarily used in oceanography and refers to the phenomenon of tidal waves having the same frequency and appearing at the same time. Some commonly used synonyms for cotidal include synchronous, coincident, coeval, and concurrent. Other related terms that are often used interchangeably with cotidal include isochronal, equitemporaneous, and simultaneous. These words all describe events or phenomena that occur at the same time or with the same frequency. While cotidal is a specific term used in the context of tidal waves, the other synonyms can be used more broadly to describe any events or actions that occur simultaneously.