[ paw-ros-i-tee, poh-, puh- ]

noun,plural po·ros·i·ties for 2.
  1. the state or quality of being porous.

  2. Geology, Engineering. the ratio, expressed as a percentage, of the volume of the pores or interstices of a substance, as a rock or rock stratum, to the total volume of the mass.

Origin of porosity

First recorded in 1350–1400; Middle English porosytee, from Medieval Latin porōsitās ; see origin at porous, -ity

word story For porosity

Porosity, “the state or quality of being porous or full of pores,” comes via Middle French and Old French porosité, porrosité from Medieval Latin porositās (stem porositāt- ), a derivative of the Medieval Latin adjective porōsus “porous,” itself a derivative of Late Latin porus “a passage, a channel in the body, an air passage.”
Porus is a borrowing of Greek póros “passage, ford, means, way out,” from the Proto-Indo-European root per-, por- (with other variants) “to lead, pass, pass over,” from which Latin derives portus “harbor” (from the sense “passage”) and portāre “to carry.” Proto-Indo-European por- becomes far- in Germanic, forming the verb faran “to wander,” Old English faran “to go, proceed, travel” (English fare ). From far-, Germanic also forms the verb farjan, Old English ferian “to carry, convey, transport” (English ferry ).
Both porous and porosity first appeared in a 14th-century English translation of a Latin encyclopedia of the sciences, an influential work that was written in the mid-13th century. The reference was to the tongue, described as being “porous and spongy.”

Words Nearby porosity

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How to use porosity in a sentence

British Dictionary definitions for porosity


/ (pɔːˈrɒsɪtɪ) /

nounplural -ties
  1. the state or condition of being porous

  2. geology the ratio of the volume of space to the total volume of a rock

Origin of porosity

C14: from Medieval Latin porōsitās, 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

Scientific definitions for porosity


[ pə-rŏsĭ-tē, pô- ]

  1. The condition of being porous.

  2. The ratio of the volume of all the pores in a material to the volume of the whole.

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