A messenger who carries military dispatches (usually on a motorcycle)(noun)
WordNet. Princeton University. 2010.
Use "dispatch rider" in a sentence
"And when the dispatch rider reported to Quintus Servilius Caepio in Tolosa, Quintus Servilius Caepio broke down and wept."
"It was the misfortune of a dispatch rider carrying a message from Narbo to find the tumbled heaps of looted corpses alongside the road through the forest just to the east of Carcasso."