| astrolabe | 1. <astronomy> An instrument for observing or showing the positions of the stars. It is now disused. Among the ancients, it was essentially the armillary sphere. A graduated circle with sights, for taking altitudes at sea, was called an astrolabe in the 18th century. It is now superseded by the quadrant and sextant. 2. A stereographic projection of the sphere on the plane of a great circle, as the equator, or a meridian; a planisphere. Origin: OE. Astrolabie, astrilabe, OF. Astrelabe, F. Astrolabe, LL. Astrolabium, fr. Gr.; star +, to take. Source: Websters Dictionary (01 Mar 1998) |
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