For reasons I cannot quite explain, I’ve always found its use pretentious, but here, nonetheless, because it occasionally turns up in English, particularly in academic prose, is a context clues worksheet on the verb aver. It means “to verify or prove to be true in pleading a cause”; “to allege or assert in pleading” and “to declare positively.” It is only used transitively.
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.