1
2
: one who traces designs, patterns, or markings
3
: a device (such as a stylus) used in tracing
4
a
: ammunition containing a chemical composition to mark the flight of projectiles by a trail of smoke or light
b
: a substance used to trace the course of a chemical or biological process
especially
: label sense 1d
Examples of tracer in a Sentence
The enemy fired tracers at the aircraft carrier.
They injected her with a radioactive tracer and tracked it via X-rays.
Recent Examples on the Web
For the study, published in Scientific Reports, researchers scanned the brains of 54 healthy women aged 40-65 using PET imaging with a tracer that binds specifically to estrogen receptors.
—
Sandra Rose Salathe, Flow Space, 25 June 2024
Smaller galaxies swarming around a larger one can be especially sensitive tracers of dark matter’s subtle effects, so cataloging and studying these satellites could be another way for researchers to learn more about how the invisible substance helped guide galactic formation and evolution.
—Phil Plait, Scientific American, 14 June 2024
Almeida admitted making trips to Mexico to get cash to buy bulk ammunition, including bullets with tracer capability.
—Beth Warren, The Courier-Journal, 12 June 2024
Massachusetts has already begun training and deploying hundreds of contact tracers, following a program the state devised in partnership with Partners in Health, a health nonprofit with long global experience working with community health workers.
—Natalia Linos, Foreign Affairs, 30 Apr. 2020
See all Example Sentences for tracer 
Sandra Rose Salathe, Flow Space, 25 June 2024
Smaller galaxies swarming around a larger one can be especially sensitive tracers of dark matter’s subtle effects, so cataloging and studying these satellites could be another way for researchers to learn more about how the invisible substance helped guide galactic formation and evolution.
—Phil Plait, Scientific American, 14 June 2024
Almeida admitted making trips to Mexico to get cash to buy bulk ammunition, including bullets with tracer capability.
—Beth Warren, The Courier-Journal, 12 June 2024
Massachusetts has already begun training and deploying hundreds of contact tracers, following a program the state devised in partnership with Partners in Health, a health nonprofit with long global experience working with community health workers.
—Natalia Linos, Foreign Affairs, 30 Apr. 2020
See all Example Sentences for tracer
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'tracer.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Dictionary Entries Near tracer
Cite this Entry
“Tracer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tracer. Accessed 15 Jul. 2024.
Copy CitationKids Definition
tracer
noun
trac·er
ˈtrā-sər 
1
a
: a person who traces missing persons or property
b
: an inquiry sent out in tracing a shipment lost in transit
2
a
: ammunition containing a chemical composition to mark the flight of projectiles by a trail of smoke or fire
b
: a substance and especially a labeled element or atom used to trace the course of a chemical or biological process
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