A lubricant is a substance used to reduce friction between moving surfaces. The property of reducing friction is known as lubricity (slipperiness).

A good lubricant possesses the following characteristics:

• Does not get affected by temperature or pressure at all
• Does not burn easily, and may also prevent rusting
• High viscosity (feels like a very thick liquid)
• Does not mix with water

The most often used lubricant is motor oil, which is used in engines of cars and motorcycles.