From Longman Dictionary of Contemporary Englishtracertrac‧er /ˈtreɪsə $ -ər/ noun [countable, uncountable] PMWa bullet that leaves a line of smoke or flame behind it
Examples from the Corpus
tracer• Scan the microwave channels to find tracer signals. 6.• As the Goshawk flight got closer they could see the flickering criss-cross of tracer.• If you saw the line of tracers from the side, then they were going somewhere else.• As the Ford charged after the Mercedes, Dunn saw in his wing mirror a spurt of tracer fire.• Suddenly tracers came back from the top.• But the tracer was weaving from side to side.• Delaney jerked the pin from a grenade, tossed it blindly in the direction of the tracer.• Begin monitoring the channels on which tracer signals were found. 8. 