Home›Browse›L›line of longitudeline of longitudeOur editors are putting together more complete content — check back in about 20 minutesline of longitudeline of longitude — nounnoun1. an imaginary line running from the North Pole to the South Pole used for measuri1.nounDefinitionan imaginary line running from the North Pole to the South Pole used for measuring east-west positionExampleThe Prime Meridian is the most famous line of longitude.