• synonyms


[ir-i-vur-suh-buh l]
  1. not reversible; incapable of being changed: His refusal is irreversible.
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Origin of irreversible

First recorded in 1620–30; ir-2 + reversible
Related formsir·re·vers·i·bil·i·ty, ir·re·vers·i·ble·ness, nounir·re·vers·i·bly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for irreversibly


  1. not able to be reversedthe irreversible flow of time
  2. not able to be revoked or repealed; irrevocable
  3. chem physics capable of changing or producing a change in one direction onlyan irreversible reaction
  4. thermodynamics (of a change, process, etc) occurring through a number of intermediate states that are not all in thermodynamic equilibrium
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Derived Formsirreversibility or irreversibleness, nounirreversibly, adverb
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 irreversibly



1620s, from assimilated form of in- (1) "not, opposite of" + reversible. Related: Irreversibly.

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Online Etymology Dictionary, © 2010 Douglas Harper