A symbol commonly used to express permeability is:

Permeability is a physical property that describes how readily a fluid can flow through a material. The symbol commonly used to represent permeability is 'k,' but in this context, the choice that correlates most closely with permeability in certain contexts, especially in fields such as electrochemistry or material science, is 'u.'

The symbol 'u' can represent a coefficient that is related to the movement of fluids or gases through porous materials, particularly in equations involving fluid dynamics or transport phenomena. In many scientific and engineering contexts, it's crucial to understand these relationships and symbols as they are foundational in fields that study the movement of fluids, including both theoretical and applied disciplines.

Understanding symbols is essential for interpreting formulas and conveying information effectively in scientific discussions, where clarity and precision are particularly important.