Bona fide
Etymology
A Latin phrase meaning "in good faith," from bona, "good" (feminine), and fide, the ablative of fides, "faith, trust." It described acting honestly and sincerely, without fraud. English kept it as both a marker of genuine good faith and, loosely, a stamp meaning "authentic."
adverb · /BOH-nuh-fyd/
Done or held in good faith; genuine and without intention to deceive.
What it names
The quality that separates a real offer, buyer, or job requirement from a sham one staged for show.
Example
The court accepted that she was a bona fide purchaser who had no way of knowing the goods were stolen.
Related idea
Acting bona fide means acting honestly; a fiduciary is held to a stricter standard still, obliged to actively serve another’s interests, not merely avoid deceit.