The term kuśala can function both as a qualifier or as a noun in its own right, which makes it difficult to resort to a single translation (I have resorted to “virtue” and “virtuous”). It refers to something beneficial or virtuous and is sometimes etymologized as something that keeps badness in check (kutsitaṁ śalate); when the sense of kuśala is more akin to “skillful” or even “virtuoso,” the etymology is that it is “someone who can cut the kuśa grass” (kuśān lāti), a type of grass that is very sharp and thus requires remarkable skill to cut it without being cut in turn.

Proper and conducive to good results.