Variant: or radio-
Function: combining form
Etymology: French, from Latin radius ray
1 : radiant energy : radiation < radio active> < radi opaque>
2 : radioactive < radio element>
3 : radium : X-rays < radio therapy>
4 : radioactive isotopes especially as produced artificially < radio carbon>
5 : radio < radio telegraphy>
6 : radius bone < radio- ulna>