Noun
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.
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.
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¡.
Source: Webster's dictionaryA good watch may serve to keep a recconing at Sea for some days and to know the time of a Celestial Observ[at]ion: and for this end a good Jewel watch may suffice till a better sort of Watch can be found out. But when the Longitude at sea is once lost, it cannot be found again by any watch. Isaac Newton
Her cutty sark, o' Paisley harn, That while a lassie she had worn, In longitude tho' sorely scanty, It was her best, and she was vauntie. Robert Burns
Achieving highly precise longitude remained a problem in geography until the application of Galileo 's Jovian moon method in the 18th century. Source: Internet
According to Ptolemy, Hipparchus measured the longitude of Spica and Regulus and other bright stars. Source: Internet
Addresses are coordinates within the system (similarly to latitude and longitude ). Source: Internet
Along parallels, each point from the surface is mapped at a distance from the central meridian that is proportional to its difference in longitude from the central meridian. Source: Internet