What is the meaning of Tracer?

A compound, element, or isotope used to track the progress or history of a natural process.

A round of ammunition for a firearm that contains magnesium or another flammable substance arranged such that it will burn and produce a visible trail when fired in the dark.

The act or state of tracking or investigating something.

A request to trace the movements of a person or an object, such as a shipment.

A person who traces something.

A device or instrument used to assist in making tracings.

to draw or plot (a diagram), to trace out

to rule (a line)

to buck up, hurry up

Source: wiktionary.org