• synonyms


  1. not compatible; unable to exist together in harmony: She asked for a divorce because they were utterly incompatible.
  2. contrary or opposed in character; discordant: incompatible colors.
  3. that cannot coexist or be conjoined.
  4. Logic.
    1. (of two or more propositions) unable to be true simultaneously.
    2. (of two or more attributes of an object) unable to belong to the object simultaneously; inconsistent.
  5. (of positions, functions, ranks, etc.) unable to be held simultaneously by one person.
  6. Medicine/Medical. of or relating to biological substances that interfere with one another physiologically, as different types of blood in a transfusion.
  7. Pharmacology. of or relating to drugs that interfere with one another chemically or physiologically and therefore cannot be mixed or prescribed together.
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  1. Usually incompatibles. incompatible persons or things.
  2. an incompatible drug or the like.
  3. incompatibles, Logic.
    1. two or more propositions that cannot be true simultaneously.
    2. two or more attributes that cannot simultaneously belong to the same object.
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Origin of incompatible

From the Medieval Latin word incompatibilis, dating back to 1555–65. See in-3, compatible
Related formsin·com·pat·i·bil·i·ty, in·com·pat·i·ble·ness, nounin·com·pat·i·bly, adverb


1. unsuitable, unsuited. See inconsistent. 1, 2. inharmonious. 2. contradictory.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for incompatibles

Historical Examples

  • He just leaves us with the juxtaposition of two incompatibles.

    A History of Mediaeval Jewish Philosophy

    Isaac Husik

  • There is somewhat which is untouched in the contention of incompatibles.

  • They are the permanent and fundamental hostilities and incompatibles.


    Ezra Pound

  • "Incompatibles can be made to agree by the authority of the Pope."

  • Phil's father and mother were among the great army of incompatibles.

    The Trail of Conflict

    Emilie Baker Loring

British Dictionary definitions for incompatibles


  1. incapable of living or existing together in peace or harmony; conflicting or antagonistic
  2. opposed in nature or quality; inconsistent
  3. (of an office, position, etc) only able to be held by one person at a time
  4. med (esp of two drugs or two types of blood) incapable of being combined or used together; antagonistic
  5. logic (of two propositions) unable to be both true at the same time
  6. (of plants)
    1. not capable of forming successful grafts
    2. incapable of fertilizing each other
  7. maths another word for inconsistent (def. 4)
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  1. (often plural) a person or thing that is incompatible with another
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Derived Formsincompatibility or incompatibleness, nounincompatibly, 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 incompatibles



mid-15c., from Medieval Latin incompatibilis, from in- "not, opposite of" (see in- (1)) + compatibilis (see compatible). Originally of benefices, "incapable of being held together;" sense of "mutually intolerant" is from 1590s. Related: Incompatibly.

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Online Etymology Dictionary, © 2010 Douglas Harper

incompatibles in Medicine


  1. Incapable of associating or blending or of being associated or blended because of disharmony, incongruity, or antagonism.
  2. Producing an undesirable effect when used in combination with a particular substance, as a medicine in combination with alcohol.
  3. Not suitable for combination or administration because of immunological differences, as blood types.
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Related formsin′com•pat•i•bili•ty (ĭn′kəm-păt′ə-bĭlĭ-tē) n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.