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

Big cats, bears, wolves, orangutans, kangaroos, birds and many other species – all dependent on humans for survival – endured unimaginable terror as Russian shells exploded around them and the skies filled with tracer fire. —Matthew Carey, Deadline, 10 July 2025

Depending on the style of tracer paper, it typically can be written on with different types of drawing media, including markers, ink pens and other sketching stationery that easily bleeds. —Bestreviews, Mercury News, 27 June 2025

Cool tech, but so much worse than the camera from behind with normal shot tracer... —Savannah Leigh Richardson, MSNBC Newsweek, 6 June 2025

Pollen is a biological marker and geographic tracer of this ancient change. —Francisca Oboh Ikuenobe, The Conversation, 20 May 2025

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