n. A conversation or discussion between three people or groups.
Bernard Lewis, has a delightful way of being self-deprecating. Thus at the outset of his 86th birthday lecture to a huge overflow audience at the Hebrew University's Truman Research Institute for the Advancement of Peace, he said "I'm just a historian dealing with the past, and to make it worse, a retired historian, so you might say my past is passe." But he went one better than that when he spoke of the trialogue attempts between Jews, Christians and Moslems.
In the finest tradition of secret societies, the Trilateral Commission has created concepts and code words that all its members can use. Their goal, said Brzezinski, is to strive for "developing sustained trilateral thought." And this they set out to do, at first for one "triennium," but since then for another three years. Members meet every nine months, rotating among the "trilateral regions" for two or three-day sessions. They pick trilateral task forces, with three rapporteurs, naturally. They conduct "trialogues" and compose policy statements called "Triangle Papers" on issues of mutual concern.
This word is a play on dialogue. Unfortunately, it doesn't quite work because di-, "two," isn't the operable prefix of dialogue. Instead, it's dia-, which means "across" or "through." Etymology rarely gets in the way of a good usage, however, and trialogue has been quite popular since the late 70s.