A petit juror is a person that sits on the jury of a civil or criminal case, as described on Britannica.com. The entirety of the jury is called a ''petit jury.'' The size of the jury panel depends on the jurisdiction, but usually ranges from six to twelve people.
Wikipedia explains that a petit jury is a panel of citizens that hears testimony and evidence to decide a trial. Before being called to sit on a case the juror will fill out a questionnaire and be asked a series of questions by the lawyers involved in order to determine if they are qualified to hear the case. The purpose of this step is to seat a panel of jurors that will decide the dispute in a fair and impartial manner. Lawyers typically have the right to have people removed from the pool of potential jurors if they feel they cannot be impartial.