What are the comparative and superlative forms of colorful?

"Colorful" is already the superlative form of "color" – it means "having the most colors" or "most colorful".

There is no comparative form of "colorful" in standard English. However, you could use phrases like:

* More colorful

* Less colorful

* More vibrant

* More varied in color

These phrases allow for degrees of colorfulness rather than simply being "colorful" or not.