dynamic surface tension

Synonym: dynamic interfacial tension

In certain circumstances, one may measure surface tensions that are different from the equilibrium value. Such a surface tension is called the dynamic surface (or interfacial) tension (γ dyn or σ dyn). The equilibrium value is then called the static surface (or interfacial) tension (γ st or σ st). The modifying signs may be omitted if there is no danger of ambiguity.
Source:
PAC, 1972, 31, 577 (Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry) on page 597