Used attributively before another noun to denote relation to longitude measurements.
Definitions
longitudenoun
The angular distance of a place east or west of the meridian at Greenwich, England, or west of the standard meridian of a celestial object, usually expressed in degrees and minutes.
The longitude of New York City is approximately 74 degrees west.
(archaic) Length or distance measured lengthwise.
In old charts, the longitude of the chamber exceeded its breadth.
longitudeadjective
Relating to, measured by, or expressed in terms of longitude.
The navigator plotted a longitude line across the chart.