1. (noun) ammunition whose flight can be observed by a trail of smoke

• tracer bullet

1. (noun) an investigator who is employed to find missing persons or missing goods

• detective
• investigator
• police detective
• tec

2. (noun) an instrument used to make tracings

• instrument

3. (noun) (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes

• radioisotope

4. (noun) ammunition whose flight can be observed by a trail of smoke

• ammo
• ammunition

1. (noun) (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes

• radiology

1. (noun) an instrument used to make tracings

• delineate
• describe
• draw
• line
• trace
• trace