the azimuth of a celestial body is the angle between the vertical plane containing it and the plane of the meridian
"The navigator adjusted his sextant to measure the precise azimuth of the sun, ensuring the calculated bearing matched the angle between the vertical plane containing the star and the plane of the meridian."
An arc of the horizon intercepted between the meridian of the place and a vertical circle passing through the center of any object.
"The surveyor adjusted his instrument to measure the azimuth before noting the precise position of the distant lighthouse relative to true north."