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
While the front office grabbed headlines during the international window by signing French superstar Antoine Griezmann for a July arrival, the current roster has to immediately plug a porous defense that has leaked a league-high 17 goals in five matches.
—
Kyle Foley, The Orlando Sentinel, 3 Apr. 2026
The Ugandan Islamist group operates on both sides of the porous border.
—ABC News, 2 Apr. 2026
Nakamura, who works almost exclusively in his native Japan, smooths over those divisions, creating reverent, porous structures that open to the landscape or curl in on themselves in repose.
—Justin Davidson, Curbed, 1 Apr. 2026
Activated charcoal, which can be derived from coconut shells, is porous and binds to odorous compounds, like bacteria and toxins.
—Bestreviews, Chicago Tribune, 31 Mar. 2026
See All Example Sentences for porous
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Kyle Foley, The Orlando Sentinel, 3 Apr. 2026
The Ugandan Islamist group operates on both sides of the porous border.
—ABC News, 2 Apr. 2026
Nakamura, who works almost exclusively in his native Japan, smooths over those divisions, creating reverent, porous structures that open to the landscape or curl in on themselves in repose.
—Justin Davidson, Curbed, 1 Apr. 2026
Activated charcoal, which can be derived from coconut shells, is porous and binds to odorous compounds, like bacteria and toxins.
—Bestreviews, Chicago Tribune, 31 Mar. 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 6 Apr. 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
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