Lubrication is the process of reducing friction between two surfaces by applying a substance, such as OIL or GREASE. GREASE (6 letters) is a thick, oily substance used to reduce friction between two surfaces. Oiling (6 letters) is the process of applying OIL to a surface to reduce friction. OIL (3 letters) is a slippery liquid that can be used to reduce friction between two surfaces. UNGUENT (7 letters) is a type of ointment used to lubricate and protect the skin. UNCTION (7 letters) is an act of applying OIL or ointment to a surface to reduce friction. All of these terms are related to the process of lubrication.