1. (n.) The imaginary great circle on the earth's surface, everywhere equally distant from the two poles, and dividing the earth's surface into two hemispheres.

2. (n.) The great circle of the celestial sphere, coincident with the plane of the earth's equator; -- so called because when the sun is in it, the days and nights are of equal length; hence called also the equinoctial, and on maps, globes, etc., the equinoctial line.

Antarctic Zone Arctic Circle Arctic Zone Frigid Zones Torrid Zone Tropic of Cancer Tropic of Capricorn Variable Zones anklet aphelion apogee armlet astronomical longitude autumnal equinox band belt bisector boundary bracelet celestial equator celestial longitude celestial meridian center cincture cingulum circle climate clime collar collarband colures core diameter diaphragm divider earring ecliptic equinoctial equinoctial circle equinoctial colure equinox fascia fillet finger ring furnace galactic longitude geocentric longitude geodetic longitude girdle girt girth great circle halfway mark heart heliocentric longitude hell hoop horse latitudes inferno interior kernel latitude line of demarcation longitude longitude in arc mean median meridian middle midmost midriff midst neckband necklace nose ring nucleus orbit oven parallel partition perigee perihelion period prime meridian quoit ring roaring forties small circle solstitial colure steam bath subtropics the line thick thick of things trajectory tropic tropics vernal equinox waist waistline wristband wristlet zodiac zone