Noun
cutlass bearing (plural cutlass bearings)
(nautical) A bearing on the drive shaft of a vessel, usually made of brass with an inner grooved rubber lining that is lubricated by the surrounding water entering the grooves as it rotates. It is a variant of the stave bearing.
When you replace a drive shaft on your boat, it is also a good idea to replace the cutlass bearing where the drive shaft exits the boat.