Word Origin & History
1530s, restored spelling of M.E. spere (c.1300) "space, conceived as a hollow globe about the world," from O.Fr. espere (13c.), from L. sphæra "globe, ball, celestial sphere," from Gk. sphaira "globe, ball," of unknown origin. Sense of "ball, body of globular form" is from late 14c. Medieval astronomical
meaning "one of the 8 (later 10) concentric, transparent, hollow globes believed to revolve around the earth and carry the heavenly bodies" is from late 14c.; the supposed harmonious sound they made rubbing against one another was the music of the spheres (late 14c.). Meaning "range of something" is first recorded c.1600 (e.g. sphere of influence (1885), in reference to British-German colonial rivalry in Africa). A spherical number (1640s) is one whose powers always terminate in the same digit as the number itself (5,6, and 10 are the only ones).