1. giving off harmful radiation as atoms break down naturally
Usage: physics; chemistry
2. containing or produced by radioactive substances

Examples

• The radioactive waste must be stored safely for thousands of years.
• Uranium is a naturally radioactive element.
• Scientists use special equipment to handle radioactive materials.
• The nuclear accident left the area radioactive and dangerous.
• Radioactive decay occurs at a predictable rate in each element.
• The hospital uses radioactive tracers to diagnose certain diseases.
• Workers wore protective suits in the radioactive zone.