celestial equator

WordReference Random House Unabridged Dictionary of American English © 2025

celes′tial equa′tor, [Astron., Navig.]

1. Astronomy, Nautical, Nautical, Astronomy, Naval Terms the great circle of the celestial sphere, lying in the same plane as the earth's equator. Also called equator, equinoctial, equinoctial circle, equinoctial line. 

• 1870–75

Collins Concise English Dictionary © HarperCollins Publishers::

celestial equator noun

1. the great circle lying on the celestial sphere, the plane of which is perpendicular to the line joining the north and south celestial poles
   Also called: equinoctial, equinoctial circle