经度 (jīng dù): longitude

Longitude is the east-west positional coordinate on the Earth's surface.

Beijing is located at 116 degrees east longitude; this longitude was measured.

When sailing, determining longitude and latitude is very important.

On a map, meridians indicate longitude, and parallels indicate latitude.

The Earth's longitude is calculated starting from the prime meridian.

Each place has a different longitude, so the time is also different.