The<unk>  is the<unk>  at which a liquid/vapor interface meets the solid surface. The<unk>  is specific for any given system and is determined by the interactions across the three interfaces. Most often the concept is illustrated with a small liquid droplet resting on a flat horizontal solid surface. The shape of the droplet is determined by the Young-Laplace equation. The<unk>  plays the role of a boundary condition.<unk>  is measured using a<unk>  goniometer. The<unk>  is not limited to a liquid/vapour interface; it is equally applicable to the interface of two liquids or two vapours. Companies such as Kyowa have developed equipment to measure microscopic<unk>  and dynamic<unk> .
Contact angle
Rape
Saturation 
Density
Action potential
Angular resolution
Position 
Molecular mass