See more synonyms for unfailing on Thesaurus.com
  1. not failing; not giving way; not falling short of expectation; completely dependable: an unfailing friend.
  2. inexhaustible; endless: unfailing resources; unfailing good humor.

Origin of unfailing

Middle English word dating back to 1350–1400; see origin at un-1, failing
Related formsun·fail·ing·ly, adverbun·fail·ing·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for unfailing


  1. not failing; unflagging
  2. continuous or unceasing
  3. sure; certain
Derived Formsunfailingly, adverbunfailingness, 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

Word Origin and History for unfailing

late 14c., "never coming to an end, unceasing," from un- (1) "not" + gerundive of fail (v.). Related: Unfailingly.

Online Etymology Dictionary, © 2010 Douglas Harper