tracer

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

Definition of tracer

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
4a : 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

Tau PET tracers are in early development, but will be useful for research and to increase knowledge gained from clinical trials testing new drugs. Scientific American, "Blood Tests for Alzheimer’s: Two Experts on Why New Studies Are Encouraging," 13 Aug. 2019 The background was a backing light made to look like the city with tracer lights for moving cars and green and red lights for traffic. Los Angeles Times, "End of an era: One of Hollywood’s last scenic painters can’t quite put down his brush," 15 Aug. 2019 Some people see minor tracers with edibles or feel utterly euphoric. Mary Schumacher, chicagotribune.com, "Old marijuana edibles: To eat or not to eat?," 15 Aug. 2019 Tau PET tracers are in early development, but will be useful for research and to increase knowledge gained from clinical trials testing new drugs. Scientific American, "Blood Tests for Alzheimer’s: Two Experts on Why New Studies Are Encouraging," 13 Aug. 2019 Tau PET tracers are in early development, but will be useful for research and to increase knowledge gained from clinical trials testing new drugs. The Conversation, oregonlive.com, "Here’s what we know about blood tests for Alzheimer’s," 10 Aug. 2019 Michael Wright, were flying near Kandahar Airfield, their Black Hawk came under machine-gun fire. Brightly lit tracer fire sliced across the sky, Wright said. Dan Lamothe, Anchorage Daily News, "How a McCain came home from war to mourn his famous father," 23 Aug. 2019 During a PET scan, a patient is injected with biologically active molecules known as tracers, which are tagged with radioactive atoms. Julie Grisham, Scientific American, "Faster, clearer PET images offer new views on disease," 9 July 2019 As the Khmer Rouge closed in, lighting up the night sky above Phnom Penh with explosions, flares and tracer bullets, he and his remaining staff were forced to evacuate on April 12, 1975, in a departure dubbed Operation Eagle Pull. Harrison Smith, Washington Post, "John Gunther Dean, ambassador haunted by U.S. departure from Cambodia, dies at 93," 11 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'tracer.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of tracer

14th century, in the meaning defined at sense 1

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Last Updated

18 Oct 2019

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

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More Definitions for tracer

tracer

noun

English Language Learners Definition of tracer

: a type of bullet that shows its path by creating smoke or light as it moves through the air
medical : a substance that is put in a patient's body so that doctors can watch a biological process (such as digestion) or see how a condition (such as cancer) is progressing

tracer

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

Medical Definition of tracer

: 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

More from Merriam-Webster on tracer

Rhyming Dictionary: Words that rhyme with tracer

Nglish: Translation of tracer for Spanish Speakers

Britannica.com: Encyclopedia article about tracer

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