known unknown

English dictionary entry

Meanings

noun
  1. An uncertainty of known magnitude, consequence, structure, and probability characteristics; something that we know that we don't know.

Word forms

known unknown known unknowns

Etymology

Popularized by Donald Rumsfeld in 2002, though used much earlier.

This entry uses open data from Wiktionary (CC BY-SA/GFDL). Word forms are used for search and are not indexed as separate pages.