A to Z GIS | Explore this related guide, featuring updated terms and graphics and developed in coordination with Esri’s GIS Dictionary team.
Learn more about A to Z GIS
GIS Dictionary
Browse dictionary
prime meridian
URL copiedShare URL
[geodesy, measurement]
The zero meridian (0°) used as the reference from which longitude east and west is measured.
[coordinate systems]
In a coordinate system, any line of longitude designated as 0 degrees east and west, to which all other meridians are referenced. The Greenwich meridian is internationally recognized as the prime meridian for most official purposes, such as civil timekeeping.