po·​rous | \ ˈpȯr-əs \

Definition of porous

1a : possessing or full of pores
b : containing vessels hardwood is porous
2a : permeable to fluids
b : permeable to outside influences
3 : capable of being penetrated porous national boundaries

Keep scrolling for more

Other Words from porous

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

Natural stone: Homeowners with natural-stone countertops like white Carrara marble or granite must be particularly careful with stains and spills since the stone can be porous. Elle Decor Staff, ELLE Decor, "How to Keep a Clean Kitchen," 28 Sep. 2011 By opposing funding for deploying troops to the border, Rep. Ruppersberger boldly goes where every Democrat has gone before—paying lip service to our troops while keeping our borders porous. WSJ, "Democrats’ Stealthy Push for Open Borders," 20 Nov. 2018 However, tile does have an Achilles heel: The grout used to fill the joints between the tiles is, by comparison, porous, relatively soft, and easily stained. Joseph Truini, Popular Mechanics, "How to Clean Dirty Grout," 5 Dec. 2018 The new products are the first application of a technology Nestle unveiled in 2016 that makes the structure of sugar more porous, so that a smaller amount produces the same sweetness. Corinne Gretler, Bloomberg.com, "Nestle to Bring Sugar-Reduction Technology to U.K.'s Milkybar," 26 Mar. 2018 Keep it porous, buoyant, and deliciously unstuck, Libra. Bess Matassa, Teen Vogue, "Weekly Horoscopes September 17-23," 10 Sep. 2016 Whiskey is aged in barrels, which are porous, and gradually loses volume through evaporation at a rate of two to four percent a year. Fox News, "Things you didn't know about whiskey," 14 Mar. 2016 The province is near the long, porous Iraqi border, making it a thoroughfare for smugglers. Benoit Faucon, WSJ, "Iran Struggles With Unrest in Pivotal Oil Hub," 28 Sep. 2018 Our porous border remains one of our greatest national security threats. Fox News, "Ken Starr: Impeachment is hell," 11 Sep. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'porous.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of porous

14th century, in the meaning defined at sense 1a

Keep scrolling for more

Learn More about porous

Statistics for porous

Last Updated

12 Jan 2019

Look-up Popularity

Time Traveler for porous

The first known use of porous was in the 14th century

See more words from the same century

Keep scrolling for more

More Definitions for porous



English Language Learners Definition of porous

: having small holes that allow air or liquid to pass through

: easy to pass or get through


po·​rous | \ ˈpȯr-əs \

Kids Definition of porous

1 : full of small holes porous wood
2 : capable of absorbing liquids porous paper


po·​rous | \ ˈpōr-əs, ˈpȯr- \

Medical Definition of porous

1 : possessing or full of pores porous bones
2 : permeable to fluids

Keep scrolling for more

More from Merriam-Webster on porous

Rhyming Dictionary: Words that rhyme with porous

Thesaurus: All synonyms and antonyms for porous

Spanish Central: Translation of porous

Nglish: Translation of porous for Spanish Speakers

Britannica English: Translation of porous for Arabic Speakers

Comments on porous

What made you want to look up porous? Please tell us where you read or heard it (including the quote, if possible).


tremendous in size, volume, or degree

Get Word of the Day daily email!

Test Your Vocabulary

Homophone Quiz

  • three-bears-two-of-them-look-like-theyre-whispering-to-a-third-bear-who-looks-chuffed-to-be-the-center-of-attention
  • In order to judge how people felt, the senator's office hired a firm to take a ______.
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!