Colure \Co*lure"\, n.; pl. Colures. [F. colure, L. coluri, pl., fr. Gr. ko`loyros dock-tailed, a"i ko`loyroi (sc. grammai` lines) the colures; fr. ko`los docked, stunted + o'yra` tail. So named because a part is always beneath the horizon.]

(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[deg] 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.

Source: Webster's Revised Unabridged Dictionary (1913)