What does infallible mean?
Infallible means incapable of making a mistake or being wrong. The word is often used to describe a person, method, rule, or judgment that is regarded as completely reliable, although such absolute certainty is often rhetorical rather than literal. In general use, it can suggest confidence so strong that the speaker may appear unwilling to consider contrary evidence. In discussions of logic and epistemology, however, infallibility has a precise meaning: a source or process that cannot produce an error under the relevant conditions. The related term fallible describes something capable of being mistaken. Infallible is especially useful when discussing reliability, authority, judgment, and the limits of human knowledge.
Incapable of making a mistake or being wrong; unfailingly accurate or reliable.
"She has an infallible memory for the names of plants."
Can be literal in philosophical discussion, but is often used figuratively as a strong, sometimes overstated compliment.
In a way that is completely accurate or reliable, without any possibility of error.
"The instrument reliably tracks the temperature change and records it infallibly."
Less common than the adjective and often used in rhetorical or technical contexts.
Calling something infallible is a high compliment—but in ordinary conversation, it can also invite the question: “Who says it never goes wrong?”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does infallible come from?
The word comes from Latin infallibilis, meaning “incapable of being deceived,” formed from in- (“not”) and fallere (“to deceive, trick”). Its development in English reflects the tradition of logic and theology, where a proposition or authority might be described as incapable of error. English cognates and related forms include fallible, fallibility, fallacious, and fallacy, all reflecting the idea of deception, mistake, or failure.
Related word forms
How infallible is actually used
Often used figuratively and sometimes rhetorically, since absolute claims of error-free reliability are rarely literal. It is common in discussion of logic, authority, methods, and personal judgment.
Easily confused with infallible
An infallible person or method cannot make errors, whereas a fallible one can be mistaken.