"Acy" is a suffix that is typically used to form nouns from adjectives. It is often used to indicate a state or quality, such as:
* Accuracy (from accurate)
* Privacy (from private)
* Efficacy (from efficacious)
* Sufficiency (from sufficient)
However, it's important to note that "acy" is not a universally applicable suffix. Its use is limited to certain adjectives and it's not always predictable when it will be used.
Therefore, "acy" is not a noun-forming suffix in the same way that suffixes like "-ness", "-ship", or "-hood" are.