Sure but can you say a bit more then about what sort of definition you’re looking for? Virtue is excellence of character. For Stoics that means acting consistently in accord with reason, and for practical purposes it’s divided into the cardinal virtues of wisdom, its most general form; justice or social virtue, which is wisdom applied to our relationships; and the two virtues of self mastery, temperance, or overcoming irrational desires; and courage/endurance, or overcoming irrational fears – these latter are required in order for us to live consistently in accord with wisdom and justice. That’s still quite a schematic definition, though. So are you looking for something else? If so, what sort of answer would satisfy you?