What does porosity mean?
Porosity is the state of being porous, or containing many small holes, spaces, or passages. It is a useful term in geology, soil science, construction, and materials engineering, where the amount and arrangement of pores can affect how a substance behaves. A porous material may allow air, water, or other fluids to move through it, although porosity and permeability are not identical: porosity describes the amount of empty space, while permeability describes how readily fluid can pass through. High-porosity materials include many sponges, lightweight concrete, and some sandstone and soil. Low-porosity materials, such as dense glass or intact granite, have less interconnected space for fluid movement. The word is also used figuratively in specialized writing to describe openness, gaps, or opportunities within a structure or system, though this usage is less common.
nounThe state or quality of being porous, meaning full of small holes or spaces through which liquids or gases may pass. In materials science and geology, it refers to the proportion of a material's volume occupied by pores.
- The quality or state of being full of pores or small openings.
- The proportion of a material's volume occupied by pores, especially in geology, soil science, and materials science.
"The high porosity of the sandstone allows groundwater to pass through it."
"Reducing the porosity of the material improved its strength."
"Measurements of the rock's porosity helped determine how much oil it could hold."
Usually uncountable in ordinary use; the plural is uncommon and is used when referring to different degrees or instances of porosity.
"The porosities of the two ceramic samples were measured under identical conditions."
A material can be porous without being easy to pass through: the holes may be present but too small or disconnected for fluids to move freely.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does porosity come from?
Porosity comes from the adjective porous, which was formed in the early 19th century from the Latin root porus, meaning “opening” or “pore.” The Latin word developed from the Greek poros, a passage or opening. The same root appears in modern forms such as porous and, in more specialized vocabulary, poriferous.
Related word forms
How porosity is actually used
Usually used in technical, scientific, or educational contexts. It is related to, but distinct from, permeability: porosity concerns the existence and amount of pore space, while permeability concerns the ease with which fluid moves through that space.
Easily confused with porosity
Porosity describes the presence and proportion of pores in a material, whereas permeability describes how readily fluid passes through it.