astrolaben.

Etymology: < (i) Anglo-Norman asterlabe, astrelaber, astrolabre, Anglo-Norman and Middle French astrelabe, Middle French astrolabe, astralabe (French astrolabe ) denoting any of various portable instruments formerly used for making astronomical measurements, especially of the altitudes of celestial objects, typically taking the form of a graduated metal disc with rotating parts and a sighting arm (c1155 in Old French as astrelabe ; 1546 denoting a similar but simpler instrument, used in navigation at sea, in later use usually distinguished by the fuller name astrolabe de mer ), and its etymon (ii) post-classical Latin astrolabium (9th or 10th cent.; frequently from 12th cent. in British sources) < Hellenistic Greek ἀστρολάβος armillary sphere, in Byzantine Greek also planisphere ( < ancient Greek ἀστρο- astro- comb. form + -λάβος -labe comb. form) + classical Latin -ium (see -y suffix⁴), perhaps influenced by the Byzantine Greek variant ἀστρολάβιον. Compare Old Occitan estralabli (late 13th cent.), astralabi (c1330), estrelabi (1506), Catalan astrolabi (14th cent.; late 13th cent. as †estrolabi), Spanish astrolabio (c1277), Portuguese astrolábio (c1508 as †astrolabeo), Italian astrolabio (1282).The α. forms largely directly reflect the French word, whose later, and now standard, form astrolabe in turn shows remodelling after the ulterior Latin etymon. The β. forms either directly reflect, or show remodelling after, post-classical Latin astrolabium; in French such forms are very rare, and are only found considerably later than in English. With the γ. forms compare Anglo-Norman astrolabre (end of the 13th cent. or earlier), asterlaber (1377), Old French astrelabre (third quarter of the 13th cent.), Middle French estalabre (1400), astalabre (1420), and also Catalan †stelabre (1345), †estelabre (1352), †estalabre (1360), †stelabri (c1410). These forms ultimately reflect the post-classical Latin variant astrolabrum (13th cent.), which may show alteration after candelabrum candelabrum n. With the δ. forms, which probably developed from the form astrolabre at γ. forms by assimilation of consonants, compare Middle French astralable (c1380) and Old Occitan estralabli (see above).