(uncountable) The noun "subtlety" represents the quality of being subtle, scarcely noticeable or difficult to discern, done in a clever and not obvious way, achieved through clever and indirect methods, and the ability to notice or understand things that are not obvious.

(countable) An instance of being subtle, a subtle thing, especially a subtle argument or distinction.

(countable, historical) An ornate medieval illusion dish or table decoration, especially when made from one thing but crafted to look like another.