planisphere noun. ['planɪsfɪǝ] LME.
[medieval Latin planisphaerium, from Latin planus PLAIN adjective¹ + sphaera, Greek sphaira SPHERE noun, in form infl. by French planisphère.]
A map, chart, or graduated scale formed by the projection of a sphere, or part of one, on a plane; esp. a polar projection of half (or more) of the celestial sphere, as in one form of astrolabe.

■ planispheric adjective of the nature of or pertaining to a planisphere M19.

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