[1] : The Collaborative International Dictionary of English v.0.48

radioactive \ra`dioac"tive\ r=a`di^-oa^k"ti^v,
   a. radio- + active.
   1. physics capable of luminescence under the action of
      cathode rays, x rays, or any of the allied forms of
      radiation. obsolete
      webster 1913 suppl.

   2. physics of, exhibiting, or caused by radioactivity.
      pjc
see also:
radioactivity 

[2] : WordNet (r) 2.0

radioactive
     adj : exhibiting or caused by radioactivity; "radioactive
           isotope"; "radioactive decay"; "radioactive fallout"
           ant: nonradioactive
see also:
nonradioactive 

Radioactive >> R Words
Radioactive, definition of term: Radioactive
radioactive_pag1.html

Radioactive Dec >> R Words
Radioactive Dec, definition of term: Radioactive Dec
radioactive+dec_pag1.html