porous

American  

[pawr-uhs, pohr-] / ˈpɔr əs, ˈpoʊr- /

adjective

1. full of pores.

2. permeable by water, air, etc.

   Synonyms:

   riddled, sievelike, pervious, penetrable

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porous British  

/ ˈpɔːrəs /

adjective

1. permeable to water, air, or other fluids

2. biology geology having pores; poriferous

3. easy to cross or penetrate

   the porous border into Thailand

   the most porous defence in the league

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porous Scientific  

/ pôr′əs /

1. Having many pores or other small spaces that can hold a gas or liquid or allow it to pass through.

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Other Word Forms

• nonporous
  adjective
• nonporousness
  noun
• porously
  adverb
• porousness
  noun
• unporous
  adjective
• unporousness
  noun

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.

Example Sentences

The paper, "A Study on Welding of Porous Metals and Metallic Foams," is published in the journal Advanced Engineering Materials.

From Science Daily • Dec. 14, 2023

Porous materials, such as wood, aren’t the best choice for spots that see a lot of humidity or rain, and painted pieces won’t last in sunny locations, where the paint can peel or crack.

From Washington Post • Apr. 27, 2021

From Peerless to Porous Even past the schedule’s halfway point, the list of marquee goaltenders having miserable seasons is surprisingly long.

From New York Times • Jan. 21, 2012

Porous or fuzzy materials are rarely used to absorb energy or deaden space in healthcare settings because they can harbor microorganisms.

From Seattle Times • Apr. 29, 2011

Porous paper makes a garment quite as warm as woolen could, and vastly lighter than the clothes you had.

From Equality by Bellamy, Edward