Mala Fide

Mala fide means bad faith, as distinct  from bona fide, in good faith. The Wiki refers to mala fides. Other sources settle for fide. It English practice fides tends to be a plural.
Mala Fide ex Wiki
Bad faith (Latin: mala fides) is double mindedness or double heartedness in duplicity, fraud, or deception.[1] It may involve intentional deceit of others, or self deception.........

Some examples of bad faith include: a company representative who negotiates with union workers while having no intent of compromising;[5] a prosecutor who argues a legal position that he knows to be false;[6] an insurer who uses language and reasoning which are deliberately misleading in order to deny a claim.[6]

Bad faith may be viewed in some cases to not involve deception, as in some kinds of hypochondria with actual physical manifestations. There is a question about the truth or falsity of statements made in bad faith self deception; for example, if hypochondriac makes a complaint about their psychosomatic health, is it true or false?[7]

Bad faith has been used as a term of art in diverse areas involving feminism,[8] racial supremacism,[9] political negotiation,[10] insurance claims processing,[6] intentionality,[11] ethics,[12] existentialism, and the law.
Perhaps the Wiki tells us too much. It is more than needed for most purposes.