tracer

American  

[trey-ser] / ˈtreɪ sər /

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 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 trace 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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Etymology

Origin of tracer

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

Example Sentences

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

From Science Daily

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

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

Oxygen isotopes function as tracers, allowing scientists to learn about water sources, plant transpiration, and atmospheric moisture.

From Science Daily

To observe brain changes, researchers used a specialized PET scan and tracer that makes cholinergic reserves visible, allowing them to measure activity before and after the training period.

From Science Daily