longitude

Definitions

1. 1.(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 74º or 4 h. 56 min. west of Greenwich.
2. 2.(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 79º. 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.

Source: Webster's Unabridged Dictionary, 1913 edition (public domain, via GCIDE / Project Gutenberg).

Synonyms

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