Meanings
nounknown unknown (plural known unknowns)
plural known unknowns
- An uncertainty of known magnitude, consequence, structure, and probability characteristics; something that we know that we don't know.
Origin
Popularized by Donald Rumsfeld in 2002, though used much earlier.
Full word history & related roots →Cite this entry
APA
known unknown. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/known%20unknown
MLA
“known unknown.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/known%20unknown. Accessed November 3, 2026.
Chicago
WatkinsX Dictionary, s.v. “known unknown,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/known%20unknown.
Source: known unknown on Wiktionary, CC BY-SA 4.0.