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tracer

[trey-ser]
noun
  1. a person or thing that traces.
  2. a person whose business or work is the tracing 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 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 through a biological, chemical, or physical system in order to study the system.
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Origin of tracer

First recorded in 1535–45; trace1 + -er1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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

British Dictionary definitions for tracer

tracer

noun
  1. 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
  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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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

Word Origin and History for tracer

n.

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.

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Online Etymology Dictionary, © 2010 Douglas Harper
tracer in Medicine

tracer

(trā′sər)
n.
  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 nerves and blood vessels.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
tracer in Science

tracer

[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. Also called label
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.