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[sem-ee-pur-mee-uh-buh l, sem-ahy-] /ˌsɛm iˈpɜr mi ə bəl, ˌsɛm aɪ-/
permeable only to certain small molecules:
a semipermeable membrane.
Origin of semipermeable
1895-1900; semi- + permeable
Related forms
semipermeability, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for semipermeable
  • Reverse-osmosis systems push water through a semipermeable membrane, which acts as an extremely fine filter.
  • Seawater is forced through a semipermeable membrane that separates salt from water.
  • Dialysis machines filter blood by pumping it out through a catheter and into a compartment with a semipermeable membrane.
  • Experiments are also under way to test encapsulated dopamine- producing cells sealed in semipermeable plastic capsules.
  • All organisms with a semipermeable membrane are subject to osmotic pressure, or the effect of water moving in and out of the cell.
British Dictionary definitions for semipermeable


(esp of a cell membrane) selectively permeable
Derived Forms
semipermeability, noun
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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semipermeable in Medicine

semipermeable sem·i·per·me·a·ble (sěm'ē-pûr'mē-ə-bəl, sěm'ī-)

  1. Partially permeable.

  2. Allowing passage of certain, especially small, molecules or ions but acting as a barrier to others. Used of biological and synthetic membranes.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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