- 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
SynonymsSee more synonyms on Thesaurus.com
1, 2. See reliable.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for infallibly
Certain causes will infallibly be succeeded by certain effects.Old-Fashioned Ethics and Common-Sense Metaphysics
William Thomas Thornton
Be it so; only, bethink you that one of us will infallibly be killed.A Hero of Our Time
M. Y. Lermontov
Ergo, again, ours must infallibly top the markets of the world.Brighter Britain! (Volume 1 of 2)
William Delisle Hay
The hand of God is raised against it and will infallibly strike it.Dona Perfecta
B. Perez Galdos
You will infallibly suspect me of having chosen them thus on purpose.Ariadne Florentina
- not fallible; not liable to error
- not liable to failure; certain; surean infallible cure
- completely dependable or trustworthy
- a person or thing that is incapable of error or failure
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 infallibly
Online Etymology Dictionary, © 2010 Douglas Harper