What is another word for the prime meridian?
Pronunciation: [ðə pɹˈa͡ɪm mɛɹˈɪdi͡ən] (IPA) 
The Prime Meridian is the line of longitude that passes through the Royal Observatory in Greenwich, London, England, and is used as the standard reference point for geographic coordinates. This line plays an essential role in international navigation and timekeeping and divides the Earth into the Eastern and Western Hemispheres. Synonyms for the Prime Meridian include the Greenwich Meridian, the Prime Vertical, and the First Meridian. These terms refer to the same imaginary line that determines the starting point for measuring longitude coordinates and serves as a reference for setting time zones around the world. The Prime Meridian is a crucial component of our modern-day global system of navigation and timekeeping.
