• synonyms


[pawr-uhs, pohr-]
  1. full of pores.
  2. permeable by water, air, etc.
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Origin of porous

1350–1400; Middle English, variant of porose < Medieval Latin porōsus. See pore2, -ous
Related formspo·rous·ly, adverbpo·rous·ness, nounnon·po·rous, adjectivenon·po·rous·ness, nounun·po·rous, adjectiveun·po·rous·ness, noun


Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for porousness

Historical Examples

  • That softness and porousness may be retained in a very easy way.

    Papers on Health

    John Kirk

  • Several Experiments to prove the porousness of Marble, and some other Stones.


    Robert Hooke

  • Experiments to prove the porousness of the skin of Vegetables.


    Robert Hooke

  • The porousness of the rocks allows it to pass under ground to the sea.

  • It can be so woven as to be almost as porous as wool, and to retain that porousness even when saturated with perspiration.

    A Handbook of Health

    Woods Hutchinson

British Dictionary definitions for porousness


  1. permeable to water, air, or other fluids
  2. biology geology having pores; poriferous
  3. easy to cross or penetratethe porous border into Thailand; the most porous defence in the league
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Derived Formsporously, adverbporousness, noun

Word Origin

C14: from Medieval Latin porōsus, from Late Latin porus pore ²
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for porousness



late 14c., "full of pores," from Old French poros (14c., Modern French poreux), from Medieval Latin porosus; or directly from Latin porus "an opening" (see pore (n.)). Figurative use from 1640s.

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Online Etymology Dictionary, © 2010 Douglas Harper

porousness in Medicine


  1. Full of or having pores.
  2. Admitting the passage of gas or liquid through pores.
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Related formsporous•ness n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

porousness in Science


  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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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.