from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Incapable of having existence or of occurring.
  • adj. Not capable of being accomplished: an impossible goal.
  • adj. Unacceptable; intolerable: impossible behavior.
  • adj. Extremely difficult to deal with or tolerate: an impossible child; an impossible situation.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Not possible, not able to be done.
  • adj. Very difficult to deal with.
  • n. an impossibility
  • n. (with definite article) that which seems impossible

from the GNU version of the Collaborative International Dictionary of English

  • adj. Not possible; incapable of being done, of existing, etc.; unattainable in the nature of things, or by means at command; insuperably difficult under the circumstances; absurd or impracticable; not feasible.
  • n. An impossibility.

from The Century Dictionary and Cyclopedia

  • Not possible; non-existent or false by necessity.
  • In law, in a stricter sense, prevented only by the act of God or a public enemy.
  • Excessively odd; not to have been imagined; such as would not have been thought possible: as, she is a most impossible person; he wears an impossible hat.
  • n. An impossibility.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. something that cannot be done
  • adj. not capable of occurring or being accomplished or dealt with
  • adj. used of persons or their behavior
  • adj. totally unlikely


Middle English, from Old French, from Latin impossibilis : in-, not; see in-1 + possibilis, possible; see possible.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From French impossible, from Latin impossibilis, from in- ("not") + possibilis ("possible"), from possum ("to be able") + suffix -ibilis ("-able"). (Wiktionary)


  • "Don't you realize that it's impossible -- _impossible_ for us to remain here?"

    The Hermit of Far End

  • "As it was impossible they should know the words, thoughts and secret actions of all men, so it was _more impossible_ they should pass judgment on them according to these things."

    How to Speak and Write Correctly

  • "You can't make me believe _that_ -- it's rubbish -- like the mango tree and rope trick -- it's impossible, simply _impossible_ to make strong-minded, level-headed people do things against their will."

    Leonie of the Jungle

  • “And after three years of secrecy and exasperation, I found that to complete it was impossible, —impossible.

    Certain First Principles

  • God, have rendered that relief physically impossible; and yet he would abrogate the poor-laws by an act of the legislature, in order to take away that _impossible_ relief, which the laws of God deny, and which the laws of man _actually_ afford.

    The Spirit of the Age Contemporary Portraits

  • "It cannot be -- it is impossible, _impossible_ that you desert a beautiful and good wife who expects your child.

    The Nest Builder

  • And, yes, we use the term impossible in its most technical sense.

    Common_Cents’s blog - RedState

  • She held her gaze on Helen, never blinking, her expression impossible to read.

    The Glass Rainbow

  • She was staring straight ahead, her expression impossible to read.

    Perfect You

  • So it came as a great surprise to the entire financial community when he came out, gave the classic Steve Jobs 'finger to the term impossible (the reason everyone loves him), and called it the iPhone - I'm sure he told his lawyers to make it happen.

    Daring Fireball


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