1. 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°.
2. The horizontal angle of an observer's bearing, measured clockwise from a reference direction such as true north.
3. The horizontal angle of a projectile's motion, measured relative to a reference direction such as true north.
[Middle English azimut, from Old French, from Arabic as-sumūt, pl. of as-samt, the way, compass bearing : al-, the + samt, way (from Latin sēmita, path; see mei-1 in the Appendix of Indo-European roots).]
az′i·muthal (-mŭthəl) adj.
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Indo-European & Semitic Roots Appendices
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