(soccer) The circle in the centre of the pitch which, at kick-off, the defending team may not enter until the attacking side has touched the ball.

An area in a field of crops where the stalks have been flattened into a circle or other geometric shape.

present participle of square the circle

(meteorology) A luminous halo, each side of the sun parallel to the horizon, caused by refraction of sunlight through ice crystals.

plural of reflecting circle

An astronomical instrument for measuring angles, like the sextant or Hadley's quadrant, by the reflection of light from two plane mirrors which it carries, and differing from the sextant chiefly in having an entire circle.

plural of polar circle

plural of Carlyle circle

(mathematics) A certain circle in a coordinate plane associated with a quadratic equation, having the property that the solutions of the equation are the horizontal coordinates of the intersections of the circle with the horizontal axis.

(astronomy) A great circle on the celestial sphere, perpendicular to the horizon, that passes through the zenith and nadir