adj. & n.
adj. 1 of, concerning, or in rays. 2 a arranged like rays or radii; having the position or direction of a radius. b having spokes or radiating lines. c acting or moving along lines diverging from a centre. 3 Anat. relating to the radius (radial artery). 4 (in full radial-ply) (of a vehicle tyre) having the core fabric layers arranged radially at right angles to the circumference and the tread strengthened.
n. 1 Anat. the radial nerve or artery. 2 a radial-ply tyre. radial engine an engine having cylinders arranged along radii. radial symmetry symmetry occurring about any number of lines or planes passing through the centre of an organism etc. radial velocity esp. Astron. the speed of motion along a radial line, esp. between a star etc. and an observer. radially adv.
[ med.L radialis (as RADIUS) ]