1
a
: possessing or full of pores
b
: containing vessels
hardwood is porous
2
a
: permeable to fluids
b
: permeable to outside influences
3
: capable of being penetrated
porous national boundaries
porously
adverb
porousness
noun
Examples of porous in a Sentence
The country has a porous border.
a cleaner that should not be used on porous surfaces
Recent Examples on the Web
The most effective modern partnerships understand that event boundaries are now porous.
—
Kate Hardcastle,
Forbes.com,
2 July 2026
The membrane, made from porous polyacrylonitrile (PAN), eliminates the need for ultrathin selective coatings traditionally required for molecular separation.
—
Jijo Malayil,
Interesting Engineering,
29 June 2026
Varela recommends using vinegar over bleach to clean mold since bleach doesn’t penetrate porous surfaces as well and can cause stains.
—
Emily Benda Gaylord,
The Spruce,
28 June 2026
Blasted from porous lava rock, the canals have to be completely full for gravity to push water across the district’s more than 42,000 acres.
—
Emily Cureton Cook,
ProPublica,
26 June 2026
See All Example Sentences for porous
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Kate Hardcastle,
Forbes.com,
2 July 2026
The membrane, made from porous polyacrylonitrile (PAN), eliminates the need for ultrathin selective coatings traditionally required for molecular separation.
—
Jijo Malayil,
Interesting Engineering,
29 June 2026
Varela recommends using vinegar over bleach to clean mold since bleach doesn’t penetrate porous surfaces as well and can cause stains.
—
Emily Benda Gaylord,
The Spruce,
28 June 2026
Blasted from porous lava rock, the canals have to be completely full for gravity to push water across the district’s more than 42,000 acres.
—
Emily Cureton Cook,
ProPublica,
26 June 2026
See All Example Sentences for porous
Cite this Entry
“Porous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/porous. Accessed 4 Jul. 2026.
Copy CitationKids Definition
porous
adjective
po·rous
ˈpōr-əs 
ˈpȯr-
1
: full of pores
2
: capable of absorbing liquids
Medical Definition
porous
adjective
po·rous
ˈpōr-əs, ˈpȯr-
1
: possessing or full of pores
porous bones
2
: permeable to fluids
Love words? Need even more definitions?
Merriam-Webster unabridged
