tracer

[ trey-ser ]

noun

1. a person or thing that traces. trace.
2. a person whose business or work is the tracing tracing trace of missing property, parcels, persons, etc.
3. an inquiry sent from point to point to trace a missing shipment, parcel, or the like, as in a transportation system.
4. any of various devices for tracing tracing trace drawings, plans, etc.
5. Also called tracer ammunition. ammunition containing a chemical substance that causes a projectile to trail smoke or fire so as to make its path visible and indicate a target to other firers, especially at night.
6. the chemical substance contained in such ammunition.
7. a substance, especially a radioactive one, traced trace through a biological, chemical, or physical system in order to study the system.

tracer

/ ˈtreɪsə /

noun

1. a person or thing that traces
2. 1. a projectile that can be observed when in flight by the burning of chemical substances in its base
   2. ammunition consisting of such projectiles
   3. ( as modifier )

      tracer fire

3. med any radioactive isotope introduced into the body to study metabolic processes, absorption, etc, by following its progress through the body with a gamma camera or other detector
4. an investigation to trace missing cargo, mail, etc

tracer

/ trā′sər /

1. An identifiable substance, such as a dye or radioactive isotope, that can be followed through the course of a mechanical, chemical, or biological process. Tracers are used in radioimmunoassays and other laboratory testing. The use of radioactive iodine, for example, can give information about thyroid gland metabolism.
2. Also called label

Word History and Origins

Origin of tracer¹

First recorded in 1535–45; trace ¹ + -er ¹

Example Sentences

The actors could watch “tracer bullets” whiz past and see explosions in midair and the eyelines would all be correct.

From Los Angeles Times

He's just doing this temporarily, working as a contact tracer in San Francisco.

From Salon

The use of fireworks, exploding targets or metallic targets, steel component ammunition, tracer or incendiary devices, and sky lanterns are prohibited.

From Seattle Times

Proulx found something similar in 2018, when he and colleagues injected tracer dyes into the cisterna magna and found they entered the systemic blood more quickly in awake mice than anesthetized ones.

From Science Magazine

Next, they used a special technique involving heavier versions of chemical elements that occur in nature as tracers to track the microbial processes.

From Science Daily