n. 分至圈

Colure \Co*lure"\ (k[-o]*l[=u]r"), n.; pl. {Colures}
(k[-o]*l[=u]rz"). [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.