permeability
pur-mee-uh-BIL-uh-tee
/ˌpɜːrmiəˈbɪləti/
The state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.
In geotechnical terms, it specifically measures how easily water can flow through soil or rock pores.
The story behind the word. Derived from the Latin 'permeabilis', from 'per' (through) and 'meare' (to go or pass). It describes the physical property of 'going through' a barrier.
Word relationships
- porousness: Porousness refers to having holes; permeability refers to those holes being connected enough to allow flow.
- impermeability: The state of not allowing any fluid to pass through.
Commonly confused with
- porosity: Porosity is the volume of 'holes'; permeability is how well those holes 'leak'.
Word family
- permeable (adjective): Allowing liquids or gases to pass through.
- permeate (verb): To spread throughout.
Collocations
- high permeability
- soil permeability
- magnetic permeability
Example sentences
- "The high permeability of the sandy soil meant that rainwater drained away almost immediately." Hydrology
- "Engineers must test the permeability of the clay before deciding if it can be used as a liner for the landfill." Civil Engineering
Memory hook
Think of a 'perm' (hair treatment) where the chemicals 'meate' (meet) and pass through the hair strands. Pass-ability.
When not to use
Do not confuse with 'porosity', which is the amount of empty space; permeability is the ability to flow through that space.
Fun facts
- Gore-Tex fabric is famous for its selective permeability—it lets sweat vapor out but keeps rain droplets from coming in.
Related words
Explore more words
permeable, aquifer, leach, transparent, conductivity, translucent
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