Astron., Surveying, etc. an angular measurement used to locate an object, star, etc.: it is measured clockwise around the horizon from the north, or south, to the object or the intersection of the object's vertical circle with the horizon
The horizontal angular distance from a reference direction, usually the northern point of the horizon, to the point where a vertical circle through a celestial body intersects the horizon, usually measured clockwise. Sometimes the southern point is used as the reference direction, and the measurement is made clockwise through 360°.
The horizontal angle of the observer's bearing in surveying, measured clockwise from a referent direction, as from the north, or from a referent celestial body, usually Polaris.