in Astrology, the dividing or distributing the heavens into 12 houses, in order to erect a theme, or horoscope, by means of six great circles, called circles of position.

There are various ways of domifying: that of Regiomontanus, which is the most common, makes the circles of position pass through the intersections of the meridian and the horizon; others make them pass through the poles of the zodiac.