Other forms: mishandled; mishandling; mishandles
When you mishandle something, you make a mess of it. For example, a teacher who mishandles a classroom loses control of his students.
An entrepreneur who mishandles an important meeting at her bank might have lost an opportunity to borrow money for her business, and a dog trainer who mishandles an aggressive dog might end up getting bitten. When you handle something, you deal with it, and when you add the Old English prefix mis-, it means that you've dealt with it in a "wrong" or "bad" way.