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[pawr-uh s, pohr-] /ˈpɔr əs, ˈpoʊr-/
full of pores.
permeable by water, air, etc.
Origin of porous
1350-1400; Middle English, variant of porose < Medieval Latin porōsus. See pore2, -ous
Related forms
porously, adverb
porousness, noun
nonporous, adjective
nonporousness, noun
unporous, adjective
unporousness, noun
2. penetrable, pervious, sievelike, riddled. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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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
  • But the porousness of the clay, which keeps the contents so deliciously cool, makes them very brittle.

    For Fortune and Glory Lewis Hough
  • Maple is a very close wood and shows but little if any porousness, therefore should never be stippled.

    Graining and Marbling Frederick Maire
British Dictionary definitions for porousness


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
Derived Forms
porously, adverb
porousness, noun
Word Origin
C14: from Medieval Latin porōsus, from Late Latin poruspore²
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
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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.

Online Etymology Dictionary, © 2010 Douglas Harper
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porousness in Medicine

porous po·rous (pôr'əs)

  1. Full of or having pores.

  2. Admitting the passage of gas or liquid through pores.

po'rous·ness n.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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porousness in Science
Having many pores or other small spaces that can hold a gas or liquid or allow it to pass through.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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