tracer

noun

trac·​er ˈtrā-sər How to pronounce tracer (audio)
1
: one that traces, tracks down, or searches out: such as
a
: a person who traces missing persons or property and especially goods lost in transit
b
: an inquiry sent out in tracing a shipment lost in transit
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

Example Sentences

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 The stories of crime-busting blockchain tracers have become part of the crypto industry’s public-relations playbook, said John Stark, a former Securities and Exchange Commission official and frequent crypto critic. David Yaffe-bellany, New York Times, 22 Apr. 2023 Plus, each bag comes with a unique tracer number for easy recovery. Madison Yauger, Peoplemag, 13 Apr. 2023 Because the satellites easily spot surfactants' smoothing effect, the substances can act as a tracer for microplastics' movements, the researchers say. Lauren J. Young, Scientific American, 26 Apr. 2023 When tracer bullets aren’t flying overhead, the land that Nelson christened Luck Ranch is a rather nice place to spend time. Jody Rosen, New York Times, 17 Aug. 2022 After the first session, they were also given a protein/carbohydrate recovery drink containing amino acids labeled with carbon-13, a non-radioactive isotope of carbon that provided a tracer for how well their muscles absorbed the drink’s amino acids. Richard A. Lovett, Outside Online, 11 Dec. 2019 The graph shows tracer binding in four areas of the brain - the lower the line, the more nicotine. Neuroskeptic, Discover Magazine, 15 May 2011 By injecting a volunteer with a radioactive tracer, such as a glucose derivative, and monitoring the radiation emitted from the brain over the next few hours, neuroscientists could see where in the brain most glucose was being absorbed - and where neural activity was happening. Neuroskeptic, Discover Magazine, 30 Aug. 2013 The ensemble cast also includes Matt Damon as Paltrow’s husband, Jude Law as a profiteering conspiracy blogger, Lawrence Fishburne as a doctor in the CDC, Kate Winslet as a contact tracer, and Marion Cotillard as a WHO epidemiologist. Harry Guinness, Outside Online, 26 Jan. 2023 See More

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.

Word History

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of tracer was in the 14th century

Dictionary Entries Near tracer

Cite this Entry

“Tracer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tracer. Accessed 9 Jun. 2023.

Kids Definition

tracer

noun
trac·​er ˈtrā-sər How to pronounce tracer (audio)
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

Medical Definition

tracer

noun
trac·​er ˈtrā-sər How to pronounce tracer (audio)
: a substance used to trace the course of a process
specifically : a labeled element or atom that can be traced throughout chemical or biological processes by its radioactivity or its unusual isotopic mass

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