Tracer

How to spell tracer

6 letters · 2 syllables

How to pronounce tracer

Say the part in capitals loudest.

What does tracer mean?

1. nounA person or instrument that follows, tracks, or copies a line, route, or item.
2. nounA bullet or shell containing a pyrotechnic charge that glows in flight to show its path.
3. nounA radioactive or otherwise detectable substance introduced into a system so its movement can be followed.

Tracer in a sentence

• The courier company employs a tracer to locate parcels that go missing in transit.

• Every fifth round in the belt was a tracer so the gunner could see where the fire landed.

• The technician injected a radioactive tracer before the scan to map blood flow through the heart.

• The architect used a light tracer to copy the outline of the old floor plan.

• The night exercise lit up the range as each tracer streaked toward the target.

• Researchers added a chemical tracer to the river to measure how quickly the water moved downstream.

Where does tracer come from?

Language of origin: French

The word builds on 'trace', which English took in the 1300s from the Old French 'tracier', meaning 'to make one's way' or 'to delineate'. That French verb descended from a Vulgar Latin form 'tractiare', itself rooted in the Latin 'tractus', 'a drawing out or dragging', the past participle of 'trahere', 'to pull or draw'. So the literal idea underneath the word is a line drawn out by pulling, which is exactly what tracing a route or a drawing involves. The agent suffix '-er' was added in English to name the person or device that traces, and the same 'trahere' root surfaces in everyday relatives like 'tractor', 'attract', and 'subtract'. In the twentieth century the noun gained technical lives: a glowing 'tracer' round whose path could be seen, and a 'tracer' substance whose movement could be followed in the body.

How the word is built

• trace (to mark out, follow a line)
• -er (agent/instrument suffix)