mala fidesPronunciation: /malə ˈfʌɪdiːz, malə ˈfiːdeɪz/Definition of mala fides noun [mass noun] Law bad faith; intent to deceive: none of the prosecutions was brought as a consequence of mala fides by the prosecutorOrigin:Latinmala fides in other Oxford dictionaries Definition of mala fides in the US English dictionary