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

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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

Gunners fans will no doubt applaud their new manager's evident determination to tighten Arsenal's porous defence. SI.com, "Arsenal Linked With Young Bundesliga Star as Unai Emery Seeks to Rebuild the Gunners' Defence," 9 July 2018 And an already porous unit loses eight of its starters heading into next season. Safid Deen, OrlandoSentinel.com, "Louisville moves on without Lamar Jackson, is No. 66 in 2018 preseason college football rankings," 22 June 2018 But as monsoon rains inundated the area, the porous limestone cave absorbed water like a sponge. Hannah Beech, Richard C. Paddock And Muktita Suhartono, New York Times, "‘Still Can’t Believe It Worked’: The Story of the Thailand Cave Rescue," 12 July 2018 The country has always had highly porous borders and contentious politics over unlawful border crossings. Peter Andreas, Washington Post, "Breaking border laws is as American as it gets," 3 July 2018 SanTan Village The splash pad's soft, porous surface is suitable for the youngest children. azcentral, "45 Phoenix area splash pads, parks and water features," 14 June 2018 Chicago has righted the ship somewhat defensively after a porous start, but its 25 goals allowed are still second-most in the Eastern Conference. Dan Mcloone, BostonGlobe.com, "Revolution look to rebound at Chicago," 8 June 2018 Fracking, short for hydraulic fracturing, uses enormous quantities of water, which drillers pressurize and shoot deep below the surface to help separate shale oil from porous rocks. Jay Root, star-telegram, "New Mexico official: Texans are 'stealing' water and selling it back for fracking," 7 June 2018 Finley picked apart Louisville’s defense last season, throwing for 367 yards on just 31 attempts and showing how porous that defense was. Jake Lourim, The Courier-Journal, "How Louisville football can (and can't) beat NC State," 12 July 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.

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First Known Use of porous

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

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Statistics for porous

Last Updated

2 Nov 2018

Look-up Popularity

Time Traveler for porous

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

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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

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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).


to express warning or disapproval

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