What does Defendant mean?
In a civil case the person or entity which is being sued is called the defendant. In a criminal case the defendant is the person who is charged with a crime. In a civil case it is up to the plaintiff to prove the defendant's actions led to their injury or loss. In a criminal case it is up to the state or the prosecutor to prove the defendant is guilty of the crime beyond a reasonable doubt.
Defendants are notified of a pending case against them after the plaintiff files a complaint which is then forwarded to the defendant. The dependant must respond to the complaint within a specified time period or the court can make a default judgment against them.
If you are the defendant in a personal injury case in some states you may also receive compensation for your injuries if you can prove the plaintiff contributed to the loss. For instance, in a comparative negligence state the amount of compensation or damages is allocated to the plaintiff and defendant based on their degree of fault.