Definitions of radial:

• noun:   pneumatic tire that has radial-ply casing
• adjective:   arranged like rays or radii; radiating from a common center

  Example: "Radial symmetry"

• adjective:   issuing in rays from a common centerXs; relating to rays of light

  Example: "Radial heat"

• adjective:   relating to or moving along or having the direction of a radius

  Example: "Radial velocity"

• adjective:   relating to or near the radius

  Example: "The radial aspect of the forearm"