What is another word for prime meridian?
Pronunciation: [pɹˈa͡ɪm mɛɹˈɪdi͡ən] (IPA) 
The prime meridian is an imaginary vertical line that passes through the north and south poles and divides the earth into the eastern and western hemispheres. Some synonyms for the prime meridian include the Greenwich meridian, which is the specific line that passes through the Royal Observatory located in Greenwich, England. Another term that is sometimes used is the zero meridian, which refers to the fact that it has been assigned a longitude value of zero degrees. The first meridian is another term that is sometimes used to describe the prime meridian, as it was the first meridian to be established as the international standard in 1884.
