A labyrinth seal is a mechanical seal that fits around a rotating shaft to prevent the leakage of oil or other fluids. A very small clearance must exist between the tips of the labyrinth threads and the running surface. A labyrinth seal is composed of many straight threads that press tightly inside another shaft, or stationary hole, so that the fluid has to pass through a long and difficult path to escape. Sometimes 'threads' exist on the outer and inner portion. These interlock, to produce the long characteristic path to slow leakage.
The name comes from the Labyrinth, an elaborate maze in Greek mythology.