Definition of: tracer

(trā′sər) noun
1. One who or that which traces.
2. One of various instruments used in tracing drawings, etc.
3. An inquiry forwarded from one point to another, to trace missing mail matter, etc.
4. Surg. An instrument for laying bare and tracing the course of nerves, muscles, etc.
5. One who searches for lost property, as on railroads.
6. Mil. a A chemical incorporated in certain types of ammunition used for ranging, signaling, or incendiary purposes. b A tracer bullet.
7. Med. A radioisotope introduced into the body for the purpose of following the processes of metabolism, the course or location of a disease, etc.
8. A message that describes a person or thing wanted, as by the police. [<TRACE¹]