tracer

noun

trac·​er ˈtrā-sər 

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

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

There are stunningly beautiful passages (tracer fire in the night sky, a drive through a forest fire) that will stick with you and needle drops (Suicide and De La Soul) that leave marks. —Taylor Antrim, Vogue, 29 Sep. 2024

Another distinguishing element is its molecular tracer technology. —Sj Studio, Sourcing Journal, 13 Sep. 2024

This helps your body use the tracer as sugar in your cells, which emits a form of energy called gamma rays. —Susan Russell, Health, 12 Sep. 2024

Intrigued, the team decided to repeat the experiment in mice using a much finer tracer: nanoparticles of gold. —Byrodrigo Pérez Ortega, science.org, 4 Sep. 2024

Word History

First Known Use

14th century, in the meaning defined at sense 1

Kids 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

Medical Definition

tracer

noun

trac·​er ˈtrā-sər 

: 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