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See more synonyms for impossible on Thesaurus.com
  1. not possible; unable to be, exist, happen, etc.
  2. unable to be done, performed, effected, etc.: an impossible assignment.
  3. incapable of being true, as a rumor.
  4. not to be done, endured, etc., with any degree of reason or propriety: an impossible situation.
  5. utterly impracticable: an impossible plan.
  6. hopelessly unsuitable, difficult, or objectionable.
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Origin of impossible

First recorded in 1250–1300; Middle English word from Latin word impossibilis. See im-2, possible
Related formsim·pos·si·ble·ness, nounim·pos·si·bly, adverb
Can be confusedimpossible impracticable impractical improbable


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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for impossible

Contemporary Examples

Historical Examples

  • The laws of the country made it impossible to accompany her beloved husband.


    Lydia Maria Child

  • Tilly was to have gone also at that time, but had found it impossible to get away.

  • Not that in his presence she became vain or petty or jealous; that would have been impossible.


    Thomas Wentworth Higginson

  • Many others are so defaced that it is impossible to decipher them.

  • If I had seen it in the pattern I should have said it was impossible for your colouring.


    William J. Locke

British Dictionary definitions for impossible


  1. incapable of being done, undertaken, or experienced
  2. incapable of occurring or happening
  3. absurd or inconceivable; unreasonableit's impossible to think of him as a bishop
  4. informal intolerable; outrageousthose children are impossible
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Derived Formsimpossibleness, nounimpossibly, 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 impossible


late 14c., from Old French impossible, from Latin impossibilis "not possible," from assimilated form of in- "not, opposite of" (see in- (1)) + possibilis (see possible). Related: Impossibly.

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Online Etymology Dictionary, © 2010 Douglas Harper