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

In desperation, Smith took out the Zaida’s automatic rifle and fired half a dozen tracer bullets over the other ship’s bow. —David Wolman, Smithsonian Magazine, 8 Jan. 2025

Plus, each bag comes with a unique tracer number for easy recovery. —Madison Yauger, People.com, 6 Jan. 2025

To remedy this, the task force's report proposed a tracer study to help understand the movement of sand in erosional areas. —George Monastiriakos, Newsweek, 30 Dec. 2024

After introducing the tracers at specific locations, the study area is periodically sampled to detect and quantify the tracers' distribution, providing insights into sediment movement over time. —George Monastiriakos, Newsweek, 30 Dec. 2024

Word History

First Known Use

14th century, in the meaning defined at sense 1

Rhymes for tracer

• acer
• baser
• chaser
• pacer
• racer
• spacer
• eraser
• replacer
• radiotracer

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