General clarity:
* Lucidity: This is probably the closest single synonym, emphasizing ease of understanding.
* Precision: Focuses on accuracy and exactness.
* Distinctness: Highlights the clear separation or differentiation of elements.
Clarity of expression:
* Perspicuity: Suggests clear and readily understandable expression.
* Articulateness: Emphasizes the skill of clear and effective communication.
Clarity of vision or thought:
* Sharpness: Suggests a clear and focused mental image.
* Definition: Highlights the clear boundaries or outlines.
The best synonym will depend on what kind of clarity you're referring to.