trialogue

trialogue [trahy-uh-lawg, -log] ExamplesWord Origin noun

1. a discussion or conversation in which three persons or groups participate.

Origin of trialogue 1525–35; tri- + (di)alogue, mistaken as a formation with di-1 Examples from the Web for trialogue Historical Examples of trialogue

These three characters carried on a conversation (trialogue) in which great truths were boldly professed.

History of the Reformation in the Sixteenth Century, Volume V

J. H. Merle d’Aubigné