Ăs'tro-lābe, n.

n. [Fr. astrolabe, N. & L. Lat. astrolabium, Sp., Pg., & It. astrolabio, Catalan astrolabi, Pr. astralabi, Gr. ἀστρολάβος, ἀστρολαβικόν, from ἄστρον, star, and λαμβάνειν, λαβεῖν, to take.] 1. (Astron.) An instrument for observing the positions of the stars, now disused. ☞ Among the ancients, it was essentially the armillary sphere. A graduated ring with sights, for-taking altitudes at sea, was formerly so called. 2. (Astrol.) A stereographic projection of the sphere on the plane of a great circle, as the equator, or a meridian. Whewell.