Mer·ca·tor pro·jec·tion / mərˈkātər/ (also Mer·ca·tor's pro·jec·tion) • n. a projection of a map of the world onto a cylinder in such a way that all the parallels of latitude have the same length as the equator, used esp. for marine charts and certain climatological maps.

Mercator projection a projection of a map of the world on to a cylinder in such a way that all the parallels of latitude have the same length as the equator, invented by the Flemish geographer and cartographer Gerardus Mercator (1512–94). It was first published in 1569 and used especially for marine charts and certain climatological maps.