'radioactive' definitions:

Definition of 'radioactive'

From: WordNet
adjective
Exhibiting or caused by radioactivity; "radioactive isotope"; "radioactive decay"; "radioactive fallout" [ant: nonradioactive]

Definition of 'radioactive'

From: GCIDE
  • radioactive \ra`di*o*ac"tive\ (r[=a]`d[i^]*[-o]*[a^]k"t[i^]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]