A phenomenon at the surface of a liquid caused by intermolecular forces WordNet 3.0 & Open English WordNet

Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Wikipedia

Tendency of a liquid surface to shrink to reduce surface area Wikidata

The force acting on the surface of a liquid, tending to minimize the area of the surface; quantitatively, the force that appears to act across a line of unit length on the surface. Also known as interfacial force; interfacial tension; surface intensity. OmegaWiki

The effect on the surface of a liquid that makes it behave as a stretched elastic membrane; it is caused by unbalanced intermolecular forces. Wiktionary

The effect on the surface of a liquid. Wiktionary (translation)