Effluent -- material exiting a system.

Elastohydrodynamic lubrication -- Lubrication modified to take into consideration the elastic properties of the bearing material and the viscosity increase of the lubricant under concentrated load. In rolling element bearings, the bearing undergoes elastic deformation (flattening) as it rolls under load in the bearing race. This momentary flattening improves the hydrodynamic lubrication properties by converting point or line contact to surface-to-surface contact.

Electrostatic separator -- a separator that removes contaminant from dielectric fluids by applying an electrical charge to the. Once charged, the contaminant is then attracted to a collection device of different electrical charge.

Emulsibility -- the ability of a non-water-soluble fluid to form an emulsion with water.

Emulsion -- intimate mixture of oil and water, generally of a milky or cloudy appearance. Emulsions may be of two types: oil-in water (where water is the continuous phase) and water-in-oil (where water is the discontinuous phase).

Environmental contaminant -- material entering a system from an operating system's external surroundings, such as dust, air, moisture or chemicals.

Erosion -- the progressive removal of a machine surface by cavitation or by particle impingement at high velocities.