Mis- means bad or badly, wrong
misbehave (v) - to act out badly or in the wrong way
mischievous (adj) - tending to make minor bad choices; teasing; full of tricks; naughty
miserable (adj) - feeling badly; the condition of feeling unhappy
misfortune (n) - bad luck
misjudge (v) - to make a wrong or unfair decision about someone
mislead (v) - to guide someone into the wrong direction; to be a bad influence
misspell (v) - to spell a word the wrong way
mistake (n) - a bad or wrong decision; error
mistreat (v) - to treat someone badly
misunderstand (v) - to think the wrong thing about what was communicated