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.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.