What is the meaning of Longitude?

Angular distance measured west or east of the prime meridian.

Any imaginary line perpendicular to the equator and part of a great circle passing through the North Pole and South Pole.

Length.

longitude

angular distance measured west or east of the Greenwich Meridian

an imaginary line perpendicular to the equator, passing through the North Pole and South Pole

Source: wiktionary.org