What is abstract noun for interesting idea?

The abstract noun for "interesting idea" depends on the specific aspect of the idea you want to emphasize:

* Novelty: Originality, Freshness, Innovation

* Intrigue: Intriguingness, Fascination, Allure

* Stimulation: Stimulation, Inspiration, Provocation

* Worth: Value, Significance, Merit

You could also use a more general abstract noun like concept, thought, or conception.

Ultimately, the best abstract noun will depend on the context of your sentence.