Forms; 4–5 azimut, azymut, 4–7 azymuth, 6 azumuth, (7 azimynth, -moth), 6– azimuth. [a. F. azimut, cogn. with It. azzimutto, Pg. azimuth, ad. Arab. as-sumūt, i.e., as = al the + sumūt, pl. of samt way, direction, a direction or point of the compass or horizon, and the arc extending from it to the zenith. Cf. samt-al-rā’s the direction or point over head, whence the term ZENITH. With the form azimynth cf. It. aziminthi (Florio).]
1. An arc of the heavens extending from zenith to the horizon which it cuts at right angles; the quadrant of a great circle of the sphere passing through the zenith and nadir, called an azimuth-circle.
c. 1391. Chaucer, Astrol., I. § 19. From this senyth … ther come a maner krokede strikes like to the clawes of a coppe … kervyng ouerthwart the almikanteras. And thise same strikes or diuisiouns ben cleped azymuthz. Thise Azimutz seruen to knowe the costes of the firmament.
1594. J. Davis, Seamans Secr., II. (1607), 8. Circles of Azumuths, or verticall circles, are quarters of great circles, concurring together in the Zenith.
1598. Sylvester, Du Bartas (1608), 299. The almycantharats, With th’ azimynths.
1651. Biggs, New Disp., ¶ 157. Severall azimuths meeting in the Zenith.
1796. Hutton, Math. Dict., I. 178/2. These azimuths are represented … on the globe by the quadrant of altitude.
1874. Moseley, Astron., ix. 45. If a great circle … be imagined to be drawn from the zenith … to the horizon, through any star … it is called the azimuth circle of that star.
2. The angular distance of any such circle from a given limit, e.g., a meridian. Hence, the true azimuth of a heavenly body is, the arc of the horizon intercepted between the north (or, in the Southern hemisphere, south) point of the horizon and the point where the great circle passing through the observed heavenly body cuts the horizon. Its magnetic azimuth is the arc intercepted between the magnetic meridian and this great circle.
Azimuth compass: a minutely divided mariner’s compass, fitted with vertical sights, used for taking the magnetic azimuth of a heavenly body: Azimuth dial: one whose gnomon is perpendicular to the plane of the horizon. Azimuth mirror: an instrument placed on the glass cover of a mariner’s compass and used for taking azimuths.
1626. Capt. Smith, Accid. Yng. Seamen, 36. Learne to obserue … the Sunnes Azimuth and Almicanter.
1697. Dampier, Voy. (1729), I. 531. The Azimuth Compass, an Instrument more peculiar to the Seamen of our Nation.
1762–9. Falconer, Shipwr., I. 740. The pilots now their azimuth attend.
1834. U. K. S., Nat. Philos., III. Astron., xiii. 255/1. The true azimuth, compared with the magnetic azimuth, will give the deviation of the compass.
b. In azimuth: in a horizontal circular direction.
1831. Brewster, Optics, xiv. 123. If we turn the steel plate round in azimuth.
1879. G. Prescott, Sp. Telephone, 269. The mirror is so mounted as to swing in azimuth.
3. transf. and fig. Horizontal angle, or direction; point of the compass.
1667. Sir R. Moray, in Phil. Trans., II. 477. Note also, at what Azimuth the Mark stands from the Gun.
1831. Brewster, Optics, xix. 167. Reflected from the second plate, at the azimuths 90° and 270°.
1860. Maury, Phys. Geog. Sea, iv. § 245. Wind gauges … to show the inclination, as well as the Azimuth of the wind.
1867. Carlyle, Remin., II. 52. How he found his way thither I know not (perhaps in a cab, if quite lost in his azimuth).
