It seems to be related to Old English cwead and Dutch kwaad, both ultimately deriving from Proto-Germanic kwēda. In Old English, the term meant "filth" or "dung", but in Dutch and subsequently German and Frisian it has a meaning of "bad, angry, melancholy", which has led some to suggest that at the time of the Quadi it meant "ferocious", though it might not be an endonym, but rather an exonym so applied because of their exacting tribute on Pannonian Germanic and Celtic tribes with whom the Romans would have had more direct contact. For the sake of my timeline though, I will be calling them the "Quadi".