An Etymological Dictionary of Astronomy and Astrophysics

In Ptolemy’s → geocentric system, an imaginary point near the center of the → deferent but at a position opposite to that of the Earth from the center of the deferent. Ptolemy further supposed that the distance from the Earth to the center of the deferent was equal to the distance from the center of the deferent to the equant. He also claimed that the planet’s deferent and the → epicycle described uniform circular motion around the equant.

Etymology (EN): L. aequant-, s. of aequans, pr.p. of aequare “to make equal.”

Etymology (PE): Falak-e mo’adel (al-masir), literally “the sphere that equalizes (the path),” from Ar. falak “celestial orbit; sphere; heaven,” from Babylonian pulluku

• mo’adel “equalizing” (+ masir “path”).