E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Originally the court of the Athenian archon, called the basileus, who used to give judgment in the stoa basilik. At Rome these courts of justice had their nave, aisles, porticoes, and tribunals; so that when used for Christian worship very little alteration was needed. The church of St. John Lateran at Rome was an ancient basilica.