Mitzvah is from the root 'tzavtah' - joining," "attachment," "connection."
Translations between any languages are a problem. But it brings up the point that because two people use the same word/s, it doesn't mean they have the same concepts in mind. This is especially true between Jews and Christians, where similarity of terms is misleading given the chasms between understandings.
How am I misunderstanding? The sites that I gave were Jewish and they call the Mitzvot commandments. Perhaps this Rabbi will convince you that I am using it in the proper sense:
"The word "mitzvah," commandment, implies a Commander. The real spiritual value of a mitzvah is when it is performed with this understanding.