Meaning of “mischief” in the English Dictionary. See all translations. uk ​ /ˈmɪs.tʃɪf/ us ​ /ˈmɪs.tʃɪf/. › [ U ] behaviour, especially a child's, that is slightly bad but is not intended to cause serious harm or damage: She's a lively little girl, full of mischief. He needs a hobby to keep him busy and stop him from getting into mischief.