The deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or people where it may be external or internal. (animations of contamination) see also decontamination, incorporation.

Contamination means that radioactive materials in the form of gases, liquids, or solids are released into the environment and contaminate people externally, internally, or both. An external surface of the body, such as the skin, can become contaminated, and if radioactive materials get inside the body through the lungs, gut, or wounds, the contaminant can become deposited internally.