<radiobiology> Generally an angle, measured around an object. ... In spherical geometries, the angle which is not the polar angle. On the earth, one incarnation of the azimuthal angle is the longitude of a location relative to the prime meridian through Greenwich, England. ... In toroidal geometries, the longitude idea still applies, but the ... Found on http://www.encyclo.co.uk/local/20973
Az'i·muth`al adjective Of or pertaining to the azimuth; in a horizontal circle. Azimuthal error of a transit instrument, its deviation in azimuth from the plane of the meridian. Found on http://www.encyclo.co.uk/webster/A/156