**Az"i*muth** (?), n. [OE. *azimut*, F. *azimut*, fr. Ar. *as-sumt*, pl. of *as-samt* a way, or perh., a point of the horizon and a circle extending to it from the zenith, *as* being the Arabic article: cf. It. *azzimutto*, Pg. *azimuth*, and Ar. *samt-al-ra's* the vertex of the heaven. Cf. Zenith.] Astron. & Geodesy (a)

The quadrant of an azimuth circle.

(b)

An arc of the horizon intercepted between the meridian of the place and a vertical circle passing through the center of any object; as, the **azimuth** of a star; the **azimuth** or bearing of a line surveying.

⇒ In trigonometrical surveying, it is customary to reckon the azimuth of a line from the south point of the horizon around by the west from 0° to 360°.

Azimuth circle, or Vertical circle, one of the great circles of the sphere intersecting each other in the zenith and nadir, and cutting the horizon at right angles. *Hutton*. -- Azimuth compass, a compass resembling the mariner's compass, but having the card divided into degrees instead of rhumbs, and having vertical sights; used for taking the magnetic azimuth of a heavenly body, in order to find, by comparison with the true azimuth, the variation of the needle. -- Azimuth dial, a dial whose stile or gnomon is at right angles to the plane of the horizon. *Hutton*. -- Magnetic azimuth, an arc of the horizon, intercepted between the vertical circle passing through any object and the magnetic meridian. This is found by observing the object with an azimuth compass.

© Webster 1913.