The doctrine that certain religious authorities or teachings are incapable of error when making official pronouncements on faith and morals. In Catholic theology, it specifically refers to the Pope's inability to err when speaking ex cathedra on matters of doctrine.
From Latin 'in-' (not) and 'fallere' (to deceive or fail), the concept developed gradually in Christian theology but was formally defined at the First Vatican Council in 1870. The term distinguishes between personal sinlessness and official doctrinal authority that cannot lead the church into error.
Papal infallibility has only been invoked twice since it was declared in 1870—once for the Immaculate Conception and once for the Assumption of Mary—making it perhaps the most powerful yet rarely used authority in religious history! The doctrine created a massive schism when it was declared, with the 'Old Catholics' breaking away because they couldn't accept that any human could be infallible. Interestingly, infallibility doesn't mean the Pope knows everything or never makes mistakes in daily life—it's specifically limited to formal doctrinal pronouncements.
Complete word intelligence in one call. Free tier — 50 lookups/day.