You may be familiar with the more commonly used "bona fide" (boh-nuh-FYE-dee), which can mean "made in good faith" (as in "a bona fide agreement") or "genuine or real" ("a bona fide miracle"). You also may have encountered the noun "bona fides," used in reference to evidence of a person's good faith, genuineness, qualifications, or achievements. Not surprisingly, in Latin bona fide means "in good faith" and mala fide means "in bad faith." These days "mala fide," which dates from the mid-16th century, tends to turn up primarily in legal contexts.