That property, due to molecular forces, which exists in the surface film of all liquids and tends to bring the contained volume into a form having the least superficial area. The thickness of this film, amounting to less than a thousandth of a millimeter, is considered to equal the radius of the sphere of molecular action, that is, the greatest distance at which there is cohesion between two particles. Particles lying below this film, being equally acted on from all sides, are in equilibrium as to forces of cohesion, but those in the film are on the whole attracted inward, and tension results.
The tendency of any liquid to pull in its open surface, so that surface is as small as possible. A function of cohesion. The attraction between molecules of a liquid that causes the surface to act as a thin elastic film under tension. Polar liquids including water have high surface tensions. Surface tension makes it possible to float a razor blade on the surface of a glass of water, even though the blade is much heavier than the water.