What is the comparative and superlative form of word dusty?

The word "dusty" is already in the positive degree. There is no comparative or superlative form for "dusty" because it's an adjective that describes a state of being covered in dust.

To express degrees of dustiness, you would use other words or phrases:

* More dusty: This is the comparative form, meaning "having more dust."

* Most dusty: This is the superlative form, meaning "having the most dust."

For example:

* Positive: The room was dusty.

* Comparative: This room is more dusty than that one.

* Superlative: This is the most dusty room in the house.