What is the noun for exceptional?

There isn't a single noun that perfectly captures the meaning of "exceptional." However, depending on the context, you could use several nouns that convey a similar idea:

For a person:

* prodigy: A person, especially a young one, endowed with exceptional talent or ability.

* genius: A person with exceptional intellectual ability.

* prodigy: A person with exceptional talent, especially in a young age.

* mastermind: A person with exceptional intelligence and cunning.

For a thing or quality:

* excellence: The state or quality of being outstanding or extremely good.

* brilliance: The quality of being brilliant or outstanding.

* virtuosity: Great technical skill, especially in the arts.

* phenomenon: An exceptional or unusual occurrence.

* wonder: A thing that causes astonishment or admiration.

* marvel: A wonderful or astonishing thing.

The best noun to use will depend on the specific context and what you want to emphasize.