means The angular distance of a place east or west of a reference meridian, measured in degrees, that fixes its position around the globe.

from From Latin 'longitudo,' meaning 'length,' from 'longus' ('long') — the same root that gives us 'long' itself. To ancient and medieval geographers, the world was 'longer' east-to-west than north-to-south, so this measure of east-west position naturally took the name for 'length,' while its perpendicular partner, latitude, came from Latin 'latitudo' ('width,' from 'latus,' 'broad').