Meaning of unknown unknown | Babel Free

Definitions

An uncertainty of unknown magnitude, consequence, structure, and probability characteristics, possibly with completely unsuspected existence; something that we don't know that we don't know.

Examples

“This means there are technical unknowns, unknown unknowns, and technical uncertainties in the contract.”

“Reports that say⟳ that something hasn't happened are always interesting to me, because as we know⟳, there are known knowns; there are things we know⟳ we know⟳. We also know⟳ there are known unknowns; that is to say⟳ we know⟳ there are some things we do not know⟳. But there are also unknown unknowns—the ones we don't know⟳ we don't know⟳. And if one looks throughout the history of our country and other free countries, it is the latter category that tend⟳ to be the difficult ones.”

“NASA officials often talk⟳ about the "unknown unknowns" – the unforeseen problems that catch⟳ them by surprise⟳.”

CEFR level