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

Tracer particles suspended in a thin electrolyte layer allowed the team to visualize and measure the movement of the fluid.

From Science Daily • Jun. 3, 2026

Tracer has taken down as many as 20,000 fake sites in a month for a client, he said.

From New York Times • Jan. 11, 2023

Whereas Soldier: 76 is a man, Tracer is a woman.

From Scientific American • Oct. 5, 2022

Kilmer voiced K.I.T.T., the sentient vehicle Tracer drives.

From Salon • Aug. 21, 2021

“Boring and uneventful,” Javier said, choosing Tracer for his first round in the game.

From "Anger Is a Gift" by Mark Oshiro