No, sloppiness (or carelessness, if you prefer) is a particular category of mistakes resulting in not paying enough attention to what you are doing while you are doing it. Either because you are distracted or are rushing to get done.

The latter is particularly common with homework that you are not interested in doing in the first place, the worst thing about it is that like many behaviors it can become habitual, and you start doing it even when the result is important to you.