porous
Americanadjective
-
full of pores.
-
permeable by water, air, etc.
- Synonyms:
- riddled, sievelike, pervious, penetrable
adjective
-
permeable to water, air, or other fluids
-
biology geology having pores; poriferous
-
easy to cross or penetrate
the porous border into Thailand
the most porous defence in the league
Other Word Forms
Etymology
Origin of porous
First recorded in 1350–1400; Middle English, variant of porose, from Medieval Latin porōsus; see pore 2, -ous
Explanation
If something is full of tiny holes or openings, you can describe it as porous. A sponge is porous, and if the border between countries is open for anyone to cross easily, it too can be called porous. You can see the word pore — meaning "a tiny opening" — in porous. When potters make a mug, they use special glazes to seal the porous clay, which otherwise would absorb the liquid you put in the mug. This meaning has expanded so porous can describe any barrier that allows easy passage in and out, like the porous border between two countries that allows residents to move easily between them.
Vocabulary lists containing porous
Can You Dig It? Words for Dirt and Soil
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"An Awful Human Trade," Vocabulary from the news article
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All Thirteen
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
It also launched a massive recruiting blitz that has sometimes resulted in porous vetting, as Slate’s Laura Jedeed discovered when ICE offered her a job after she skipped several screening steps.
From Slate ● Jul. 14, 2026
In those experiments, sodium chloride crystals form in a loose, porous structure as water evaporates.
From Science Daily ● May 31, 2026
India shares a long and porous border with Bangladesh, where migration has historically been driven by economic hardship and longstanding family links.
From Barron's ● May 29, 2026
The forests are dense and the region's porous borders make it easy for the militants to set up bases and to move across countries without being detected by the security forces.
From BBC ● Apr. 9, 2026
The slopes and low hills that fell gently toward the river only appeared welcoming; underneath vines, carpet grass, wild grape, hibiscus and wood sorrel, the ground was as porous as a sieve.
From "Jazz" by Toni Morrison
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
