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[trey-ser] /ˈtreɪ sər/
a person or thing that traces.
a person whose business or work is the tracing of missing property, parcels, persons, etc.
an inquiry sent from point to point to trace a missing shipment, parcel, or the like, as in a transportation system.
any of various devices for tracing drawings, plans, etc.
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.
the chemical substance contained in such ammunition.
a substance, especially a radioactive one, traced through a biological, chemical, or physical system in order to study the system.
Origin of tracer
First recorded in 1535-45; trace1 + -er1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for tracer
Contemporary Examples
Historical Examples
  • It was a hellishly unbuildable and deceptively simple gadget, that tracer.

    Zero Data Charles Saphro
  • That there tracer started to hum again soon after you was out for a while.

    Zero Data Charles Saphro
  • He didn't know that there was a German in the sky, until he saw the tracer bullets.

    High Adventure James Norman Hall
  • Anything that goes out through it will have a tracer slapped onto it.

    Skylark Three Edward Elmer Smith
  • Then build me a tracer detector that'll pick it up at high velocity.

    Skylark Three Edward Elmer Smith
  • We discovered tonight that some kind of tracer material had been worked into all your clothes.

    Legacy James H Schmitz
  • Then work on the dry surface with tracer and stamps, as you would on wood or brass.

    A Manual of Wood Carving Charles G. Leland
British Dictionary definitions for tracer


a person or thing that traces
  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
(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
an investigation to trace missing cargo, mail, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for tracer

c.1500, "one who tracks or searches," agent noun from verb form of trace (n.1). Meaning "bullet whose course is made visible" is from 1910.

Online Etymology Dictionary, © 2010 Douglas Harper
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tracer in Medicine

tracer trac·er (trā'sər)

  1. A substance, such as a dye or a radioactive isotope, that is introduced into and followed through a biological or chemical process, by virtue of its radioactive signature, color, or other distinguishing physical property, thus providing information on the course of the process or on the components or events involved.

  2. An instrument used in dissecting out nerves and blood vessels.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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tracer in Science
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. Also called label.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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