celestial longitude

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The angular distance eastward from the vernal equinox measured along the ecliptic to a great circle drawn through the pole of the ecliptic plane and a celestial body.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours and minutes and seconds; used with declination to specify positions on the celestial sphere