What does dunno mean?
Dunno is an informal contraction of "I don't know," functioning chiefly as a conversational reply that signals ignorance, uncertainty, or simple lack of interest. It appears almost exclusively in speech and informal writing — dialogue in fiction, text messages, emails between friends — where it lends a relaxed, colloquial tone. A speaker might say "Dunno, ask her" when asked for directions they don't have, or "Dunno why it broke" when puzzling over a fault. Beyond mere ignorance, it can carry a dismissive or evasive edge, brushing off a question the speaker would rather not engage with. Though long established in everyday British and American speech, it remains firmly non-standard: it belongs to the same register as "gonna" and "wanna" and should be avoided in formal contexts. Its very informality is its value — no other word conveys casual unknowing quite as economically.
interjectionAn informal contraction of "I don't know," used to express uncertainty, ignorance, or indifference.
- An informal spoken contraction of "I don't know," expressing ignorance or uncertainty.
- A dismissive or evasive reply indicating unwillingness to engage with a question.
""Where'd he go?" "Dunno — maybe the library.""
""What time does the film start?" "Dunno — check the website.""
"She shrugged and said she dunno what all the fuss was about."
Dunno is one of English's most honest words — a single casual syllable-pair that shrugs off an entire question.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dunno
Dunno arose as a natural spoken reduction of "I don't know," with the vowel of "do" reducing and merging into the following consonant, much like "gonna" from "going to." It developed organically in everyday English speech, becoming widespread in both Britain and America by the nineteenth and early twentieth centuries, though precise first-attestation dates are uncertain. It shares its ultimate root with the verb "know," from Old English "cnāwan," which also gives us related words such as "knowledge" and "acknowledge."
How dunno is actually used
Strictly informal and conversational; avoid in formal writing. Common in both British and American speech, often in dialogue or casual text messages. It typically stands alone as a reply rather than appearing mid-sentence in careful prose.
Easily confused with dunno
"Don't know" is the full standard phrase, while "dunno" is its informal spoken contraction.