Lacquer -- a deposit resulting from the oxidation and polymerization of fuels and lubricants when exposed to high temperatures. Similar to, but harder than, varnish.

Laminar particle – wear analysis-specific term for very thin free metal flakes which are generated during the life of a rolling element bearing, but whose increased presence is generally accepted as preceding deep spalling.

Liquid -- any substance that flows readily or changes in response to the smallest influence. More generally, any substance in which the force required to produce a deformation depends on the rate of deformation rather than on the magnitude of the deformation.

Load-carrying capacity -- property of a lubricant to form a film on the lubricated surface, which resists rupture under given load conditions. Expressed as maximum load the lubricated system can support without failure or excessive wear.

Lubricant -- any usually oily liquid or solid of vegetable, animal, mineral or synthetic origin that reduces friction, heat and wear when applied to the surfaces of moving parts.

Lubricity -- ability of an oil or grease to lubricate; also called film strength.