tracer
/ˈtreɪsər/
noun
- A substance or device used to track the movement or location of something, such as a dye, radioactive material, or tracking tag.
- The wildlife team attached a GPS tracer to the bear's collar.
- Doctors used a radioactive tracer to see how the patient's kidneys were functioning.
- The scientists injected a fluorescent tracer into the river to study water flow.
- A bullet or projectile that leaves a visible trail of light or smoke so its path can be seen.
- At night, the tracers lit up the sky like streaks of fire.
- The soldier loaded a few tracer rounds into the magazine to check his aim.
- The shooter used tracers to adjust the machine gun's trajectory.
- A person or thing that finds or follows something, such as a detective or a tracking dog.
- The tracer followed the missing hiker's footprints through the snow.
- The bloodhound was an excellent tracer, never losing a scent.
- She worked as a tracer for a missing persons organization.