NCC-73918 was the registry number of a Federation Danube-class runabout that was in service with Starfleet in the late 24th century, attached to Deep Space 9.
In 2375, Kira Nerys, Odo and Elim Garak used it to enter Cardassian space to assist the Cardassian Rebellion. Along with Damar and Rusot they later rendezvoused with a Cardassian shuttle. (DS9: "Tacking Into the Wind")
Runabouts are usually named, but this one was never referred to by any name – just the registry readable off of its hull.