Definition of grease nipple in English English dictionary
A fitting fixed to a piece of machinery, used as an inlet for lubricating grease by means of a grease gun
A grease fitting, grease nipple or zerk fitting is a lubrication fitting used in mechanical systems to add grease with a grease gun. The fitting is permanently installed by a threaded connection leaving a nipple connection the grease gun attaches to. By using the pressure in the grease gun, grease is added to the system through the grease fitting. The patent for the zerk fitting was granted to Oscar Zerk in January 1929