A person charged with a crime is being brought to the CRIMINAL courts by the state. If convicted that person may be fined or sent to prison.
A person being sued is being brought to the CIVIL courts by another legal person. The side which loses the case will have to pay costs and perhaps make restitution to the person who wins.
In either a civil or criminal case, the person accused of wrong is the defendant.
the Defendant
the defendent
The suspect - or - The accused !
Petitioner
Petitioner
Defendant. He has to defend him self against the plaintiff's accusation.
Has been charged with a crime in a criminal case or is the person being sued in a civil case.
In a criminal case it is the accuser. In a civil case - think Judge Judy - it is the Plaintiff
Plantiff
The person that commited the crime
The person a case is held against is the "Defendant". The person holding the case against them is known as the "Plaintiff".
the person who files against you. the complainant
Civil Case
A person or Party begins a civil case against another party by a complaint being introduced. This complaint must be shown to the Court House where it is decided to be ruled or not. To begin a civil case or complaint against another party, the complainant/plaintiff must file a lawsuit/complaint in court to initiate the case. This would also involve paying the proper filing fees and yes, often, a lawyer would be necessary in order to prepare your pleading.
That will depend on whether the case is a civil or criminal trial. In a civil court case the two sides are the defendant and the plaintiff. For a criminal court it will be the defendant (the accused) and the government entity bringing the charges, usually the State or Country.