(n): a police officer who investigates crimes
(n): an instrument used to make tracings
(n): a device that requires skill for proper use
(n): (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes
(n): a radioactive isotope of an element; produced either naturally or artificially
(n): ammunition whose flight can be observed by a trail of smoke
(n): projectiles to be fired from a gun