"Where's the remote?" "Dunno." Dunno is a contraction of "don't know." It is casual, quick, and slightly lazy. It is not a word you write in an essay. It is a word you say when you cannot be bothered to pronounce the full phrase. It has been in English since the 1800s. It appears in dialogue in novels. It is common in texting.

Dunno is not rude. It is just informal. It can be a shrug in word form. It says, "I have no information, and I am not going to look." It can also be a deflection. "Dunno" can avoid a difficult question. It is a small door that closes a conversation.

Similar contractions

• Gonna: going to.
• Wanna: want to.
• Gotta: got to.
• Lemme: let me.

Dunno is part of a family of contractions that make English faster. They are not errors. They are features. They show how language adapts to speed. In formal writing, use the full phrase. In speech, dunno is fine. It is honest. It is human.