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 team’s run defense has been porous to start the season and could get worse following the torn bicep suffered by defensive tackle Ed Oliver; Bills head coach Sean McDermott confirmed Oliver would undergo surgery and will be out indefinitely.
—
Ben Morse, CNN Money, 29 Oct. 2025
Iraq shares a porous 994-mile border with Iran, after all; the prime minister has to balance the interests of this powerful neighbor against those of an even more powerful partner in Washington.
—Robert F. Worth, The Atlantic, 28 Oct. 2025
Other existing techniques, including catalytic pyrolysis and one-pot synthesis, are known to enable the production of structurally superior carbon nanotubes and porous carbon.
—Mrigakshi Dixit, Interesting Engineering, 28 Oct. 2025
That is, unless star tailback Bijan Robinson decides to break the rushing record against this porous Dolphins defense.
—Miami Herald, 25 Oct. 2025
See All Example Sentences for porous
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Ben Morse, CNN Money, 29 Oct. 2025
Iraq shares a porous 994-mile border with Iran, after all; the prime minister has to balance the interests of this powerful neighbor against those of an even more powerful partner in Washington.
—Robert F. Worth, The Atlantic, 28 Oct. 2025
Other existing techniques, including catalytic pyrolysis and one-pot synthesis, are known to enable the production of structurally superior carbon nanotubes and porous carbon.
—Mrigakshi Dixit, Interesting Engineering, 28 Oct. 2025
That is, unless star tailback Bijan Robinson decides to break the rushing record against this porous Dolphins defense.
—Miami Herald, 25 Oct. 2025
See All Example Sentences for porous
Cite this Entry
“Porous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/porous. Accessed 1 Nov. 2025.
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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