ˈ ̷ ̷| ̷ ̷ ̷ ̷ noun
Etymology: Middle English graunde jurie, literally, large jury, from Anglo-French graund jurre
1. : a body of from 12 to 23 good and lawful persons of a county who are returned in England by the sheriff to every session of the peace and of the assizes and in federal courts in the United States and in some state courts are impaneled usually at intervals of a month or more to serve continuously until the next impanelment and whose duty it is to examine in private sessions accusations against persons charged with crime, to find bills of indictment against them to be presented to the court if they see just cause, and to act on such other public matters as may be brought before them — compare petit jury
2. : one that investigates crime in the manner of a grand jury
appointed himself a one-man grand jury to bring the criminals to justice