Longitude

n.
  1. Length; measure or distance along the longest line; -- distinguished from breadth or thickness; as, the longitude of a room; rare now, except in a humorous sense.
  2. (Geog.) The arc or portion of the equator intersected between the meridian of a given place and the meridian of some other place from which longitude is reckoned, as from Greenwich, England, or sometimes from the capital of a country, as from Washington or Paris. The longitude of a place is expressed either in degrees or in time; as, that of New York is 74° or 4 h. 56 min. west of Greenwich.
  3. (Astron.) The distance in degrees, reckoned from the vernal equinox, on the ecliptic, to a circle at right angles to the ecliptic passing through the heavenly body whose longitude is designated; as, the longitude of Capella is 79°.
    4. Geocentric longitude (Astron.),
    the longitude of a heavenly body as seen from the earth.
    Heliocentric longitude ,
    the longitude of a heavenly body, as seen from the sun's center.
    Longitude stars ,
    certain stars whose position is known, and the data in regard to which are used in observations for finding the longitude, as by lunar distances.