ˈreɪdjəs n. & v. --n. (pl.
radii or radiuses) 1
Math. a a
straight line
from the centre to the
circumference of a
circle or
sphere. b a
radial line from the
focus to
any point of a
curve. c the
length of the radius of a circle etc. 2 a usu. specified
distance from a centre in
all directions (within a radius of 20 miles;
has a
large radius of action). 3 a the thicker
and shorter of the
two bones in the
human forearm (cf. ULNA). b the corresponding
bone in a vertebrate's
foreleg or a bird's
wing. 4 any of the
five arm-like structures of a
starfish. 5 a any of a set of lines diverging from a point like the radii of a circle. b an
object of
this kind, e.g. a spoke. 6 a the
outer rim of a
composite flower-head, e.g. a
daisy. b a radiating
branch of an
umbel. --v.tr.
give a rounded
form to (an
edge etc.). øradius
vector Math. a
variable line
drawn from a fixed point to an
orbit or
other curve, or to any point as an
indication of the latter's
position. [L, = staff, spoke, ray]
