Co·lure n.; pl. Colures   Astron. & Geog. One of two great circles intersecting at right angles in the poles of the equator. One of them passes through the equinoctial points, and hence is denominated the equinoctial colure; the other intersects the equator at the distance of 90° from the former, and is called the solstitial colure.
 Thrice the equinoctial line
 He circled; four times crossed the car of night
 From pole to pole, traversing each colure.   --Milton.
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