tracer

American  

[trey-ser] / ˈtreɪ sər /

noun

• tracers
  plural

1. a person or thing that traces.

2. a person whose business or work is the tracing 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 drawings, plans, etc.

5. Also called tracer ammunition.  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 through a biological, chemical, or physical system in order to study the system.

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tracer British  

/ 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

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tracer Scientific  

/ 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

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Other Word Forms

Noun Inflected Forms

• tracers
  plural

Etymology

Origin of tracer

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

Example Sentences

See Examples For:

tracer tracers

Dr Whitaker adds that the scans and tracer involve exposure to radiation, which needs consideration and to be put in the context of the risks of having a laparoscopy for example.

From BBC ● Apr. 29, 2026

A review of several studies found that the average cost per measles case is $43,203, and each person who has to be notified by a contact tracer after exposure costs $443.

From MarketWatch ● Dec. 17, 2025

Overnight, AFP journalists saw Ukraine using tracer bullets and missile defence systems, and incandescent debris falling over large areas above the capital.

From Barron's ● Nov. 14, 2025

"The Neuro is one of the few centres worldwide that can produce the tracer and run the scan."

From Science Daily ● Oct. 29, 2025

You stare out at tracer rounds unwinding through the dark like brilliant red ribbons.

From "The Things They Carried" by Tim O'Brien

Hydrogen rich galaxies also serve as effective tracers of how gas moves along cosmic filaments.

From Science Daily ● Dec. 25, 2025

In February he underwent a scan that uses radioactive tracers to see if it had spread.

From Los Angeles Times ● Apr. 27, 2025

Alzheimer's disease pathology was measured using PET scans with tracers that bind to amyloid plaques and tau tangles that accumulate in the brains of people with Alzheimer's disease.

From Science Daily ● Dec. 2, 2024

In fact, scientists have been doing studies like this since the 1960s, releasing tracers such as zinc sulfide powder or sulfur hexafluoride gas into the stratosphere to study air currents.

From Scientific American ● Sep. 20, 2023

That was a good thing, because no one paid attention to me in the seat against the wall, picking through my food for Communist tracers.

From "Made You Up" by Francesca Zappia