prefix meaning "bad, badly, ill," from Fr., from O.Fr. mal "evil, ill, wrong, wrongly," from L. male (adv.) "badly," or malus (adj.) "bad, evil" (fem. mala, neut. malum), of unknown origin, perhaps related to Avestan mairiia "treacherous." Most Mod.Eng. words with this prefix are 19c. coinages (malnutrition, malodorous, etc.).