ligne équinoxialecommon nounEtymologyexpandsee line and equinoctialDefinitions1. A line that is supposed to be drawn on the entire surface of the globe, and so named because, when the sun describes its circle perpendicularly on this line, the days are everywhere equal to the nights.expand2. Part of this line that is sometimes actually drawn on the ground for some astronomical observations, as can be seen in the Saint-Sulpice church in Paris.by extensionexpandSynonymséquateurgnomon