DUNNO

Etymology

Contraction

dunno

Eye dialect spelling of do not know; eye dialect spelling of does not know.

Usage notes

This is one of the only verb forms in English that regularly does not require a pronoun. When the pronoun is not given, it is assumed to be I; all other pronouns must be given. It is never mandatory to drop I, although it is most common to do so when dunno is the only word in the sentence.

Noun

dunno (plural dunnos)

An utterance of the word dunno.

Source: Wiktionary