Answer: a word (other than a pronoun) used to identify any of a class of people, places, or things ( common noun ), or to name a particular one of these ( proper noun ).
-definition from G0ogle
Explanation:
Answer:it's related to how everything has it's own purpose with all it's connections
I think this is classified as a Idiom
Well saying dunno is an error in formal/academic writing. In academic writing you would have to write, i do not know, though.