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[rig-er-uh s]
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  1. characterized by rigor; rigidly severe or harsh, as people, rules, or discipline: rigorous laws.
  2. severely exact or accurate; precise: rigorous research.
  3. (of weather or climate) uncomfortably severe or harsh; extremely inclement.
  4. Logic, Mathematics. logically valid.

Origin of rigorous

First recorded in 1350–1400; Middle English word from Medieval Latin word rigōrōsus. See rigor, -ous
Related formsrig·or·ous·ly, adverbrig·or·ous·ness, nouno·ver·rig·or·ous, adjectiveo·ver·rig·or·ous·ly, adverbo·ver·rig·or·ous·ness, nounself-rig·or·ous, adjectivesem·i·rig·or·ous, adjectivesem·i·rig·or·ous·ly, adverbsem·i·rig·or·ous·ness, nounun·rig·or·ous, adjectiveun·rig·or·ous·ly, adverbun·rig·or·ous·ness, noun


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1. stern, austere, hard, inflexible, stiff, unyielding. See strict. 2. demanding, finical. 3. hard, bitter.


1. flexible, soft. 2. inaccurate. 3. mild.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for rigorous


  1. characterized by or proceeding from rigour; harsh, strict, or severerigorous discipline
  2. severely accurate; scrupulousrigorous book-keeping
  3. (esp of weather) extreme or harsh
  4. maths logic (of a proof) making the validity of the successive steps completely explicit
Derived Formsrigorously, adverbrigorousness, 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 rigorous


late 14c., from Old French rigorous (13c., Modern French rigoureux), from Medieval Latin rigorosus, from Latin rigor (see rigor). Related: Rigorously.

Online Etymology Dictionary, © 2010 Douglas Harper