longitude
Plurallongitudes
- 1Angular distance east or west of the prime meridian, used to fix a position on Earth.
Determining longitude accurately at sea remained a major problem until the marine chronometer was invented.
The two cities lie at nearly the same longitude but at very different latitudes.
Note
Measured in degrees, it runs from 0° at Greenwich to 180° on the far side of the globe, and is always given with a direction: 74° W. The word is countable for a particular reading (a longitude of 30° E) and uncountable for the quantity itself (finding longitude at sea). Its Latin source, longitudo, simply meant "length", the meaning that survives in the archaic sense of length.
- 2An imaginary line perpendicular to the equator, forming part of a great circle that passes through both the North and South Poles.
Each longitude runs from pole to pole, crossing the equator at a right angle.
The chart was ruled with longitudes spaced ten degrees apart.
Similarmeridian
Note
Here the word names the line rather than the measurement: a pole-to-pole half of a great circle, the same thing geographers and astronomers also call a meridian. Every point along one shares a single value of the angular measure. In this use the word is freely countable (longitudes ruled ten degrees apart), and meridian can usually stand in for it without any change in meaning.
- 3The length or linear extent of a thing.
The scholar described the longitude of the table in careful detail.
His shoulders are remarkably sloping, giving an appearance of great longitude to his neck.
1831, Francis Griffin, “Griffin's Remains”Note
An older use that keeps the Latin meaning of plain physical length. Francis Griffin could still write in 1831 of sloping shoulders "giving an appearance of great longitude" to a neck. Today the word reads as elevated or playfully learned. In ordinary prose, length is the word to use. Save longitude for period color or deliberate mock-grandeur, where its bookish ring is the point.
Practice
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Origin
From Middle English, borrowed via Old French longitude from Latin longitūdō ("length, a measured length"), which comes from longus ("long").