s more particularly applied in astronomy to the several systems of the heavens; or the different ways in which different astronomers have supposed the heavenly bodies to be ranged, moved, &c.

The principal hypotheses are the Ptolemaic, Copernican, and Tychoonic. The Copernican is now become so current, and is so well warranted by observation, that the retainers thereto hold it injurious to call it an hypothesis. See ASTRONOMY.