ra·di·al (rādē-ăl) 1. Relating to the radius (bone of the forearm), to any structures named from it, or to the radial or ... ra·di·al. (rādē-ăl), 1. Relating to the radius (bone of the forearm), to any structures named from it, or to the radial or ... ra′di·al·ly adv.. The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by ... Radial Spoke Protein 4. *radial step. *radial step. *radial step. *Radial stress ...