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See more synonyms for ill-founded on Thesaurus.com
  1. based on weak evidence, illogical reasoning, or the like: an ill-founded theory.
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Origin of ill-founded

First recorded in 1665–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


Examples from the Web for ill-founded

Historical Examples

  • And Artois said to himself that the faint suspicion he had had was ill-founded.

    A Spirit in Prison

    Robert Hichens

  • The problem did not seem to puzzle her, the problem of this feeling so ill-founded.

    The Call of the Blood

    Robert Smythe Hichens

  • It will be seen hereafter, that this apprehension was not ill-founded.

  • Well, all that would be ill-founded, unjust, and contrary to truth.

  • It has met the fears of dying men, by giving a system to their ill-founded hopes.


    Edward Hoare

British Dictionary definitions for ill-founded


  1. not founded on true or reliable premises; unsubstantiatedan ill-founded rumour
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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