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Supposedly vs. Supposably


[in-fal-uh-buh l] /ɪnˈfæl ə bəl/
absolutely trustworthy or sure:
an infallible rule.
unfailing in effectiveness or operation; certain:
an infallible remedy.
not fallible; exempt from liability to error, as persons, their judgment, or pronouncements:
an infallible principle.
Roman Catholic Church. immune from fallacy or liability to error in expounding matters of faith or morals by virtue of the promise made by Christ to the Church.
an infallible person or thing.
Origin of infallible
late Middle English
1375-1425; late Middle English < Medieval Latin infallibilis. See in-3, fallible
Related forms
infallibility, infallibleness, noun
infallibly, adverb
noninfallible, adjective
noninfallibly, adverb
1, 2. See reliable. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for infallibly
Historical Examples
  • Vanity is plainly her predominant passion, and, if you will administer to that, it will infallibly throw her into your arms.

    Amelia Henry Fielding
  • Be it so; only, bethink you that one of us will infallibly be killed.

    A Hero of Our Time M. Y. Lermontov
  • But it does not appear that these processes are infallibly efficacious, nor, above all, easy to employ.

    The Insect World Louis Figuier
  • Ergo, again, ours must infallibly top the markets of the world.

    Brighter Britain! (Volume 1 of 2) William Delisle Hay
  • We should infallibly have understood each other, and should hardly have agreed together long.

  • He looked what he was—unconquerable; and if she had not loved him already, she must infallibly have loved him then.

  • The smoke of this infallibly kills them, and the smell keeps others away for several days.

    The History of Louisiana Le Page Du Pratz
  • We've got a woman who knows, infallibly, who's going to marry whom!

    Talents, Incorporated William Fitzgerald Jenkins
  • If not, 'their restoration is possible, and they will infallibly have all their evil removed out of them by the goodness of God.'

    The English Church in the Eighteenth Century Charles J. Abbey and John H. Overton
  • He who adventures into them without a guide is infallibly lost.

British Dictionary definitions for infallibly


not fallible; not liable to error
not liable to failure; certain; sure: an infallible cure
completely dependable or trustworthy
a person or thing that is incapable of error or failure
Derived Forms
infallibility, infallibleness, noun
infallibly, 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
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Word Origin and History for infallibly



early 15c., from Medieval Latin infallibilis, from in- "not, opposite of" (see in- (1)) + Late Latin fallibilis (see fallible). In reference to Popes, attested from 1870. Related: Infallibly.

Online Etymology Dictionary, © 2010 Douglas Harper
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