Siaynoq was a religious orgiastic, ecstatic sexual experience involving Fish Speaker leaders who were called to Arrakis every ten years to commune with the God Emperor Leto II in his Fesitval City of Onn.
Every 10 years the women leaders of were gathered together from all over the Imperium, in a large amphitheater that Leto had built on Arrakis. The women were arranged in a giant circle, and the God Emperor would appear. After 3 to 4 hours of chanting Leto's name, and hearing him speak to them in intimate ways, the women would crescendo in an ecstatic ritual with Leto as their focus.
It is rumored that after Leto's death, and the subsequent colonization of planets by the Fish Speakers during The Scattering, that the remnant and corruption of the concepts of Sianyoq, became one of the foundations of the Honored Matres sexual enslavement of males.
"The ritual is called Siaynoq-the Feast of Leto. It is the adoration of my person in my presence."
"An ancient ritual, Lord?"
"It was with the Fremen before they were Fremen. But the keys to the Festival secrets died with the old ones. Only I remember them now. I recreate the Festival in my own likeness and for my own ends."
"Then the Museum Fremen do not use this ritual?"
"Never. It is mine and mine alone. I claim eternal right to it because I am that ritual."
"It is a strange word, Lord. I have never heard its like."
"It has many meanings, Moneo. If I tell them to you, will you hold them secret?"
"My Lord commands!"
"Never share this with another nor reveal to the Fish Speakers what I tell you now."
"I swear it, Lord."
"Very well. Siaynoq means giving honor to one who speaks with sincerity. It signifies the remembrance of things which are spoken with sincerity."
"But, Lord, doesn't sincerity really mean that the speaker believes... has faith in what is said?"
"Yes, but Siaynoq also contains the idea of light as that which reveals reality. You continue to shine light on what you see."
"Reality... that is a very ambiguous word, Lord."
"Indeed! But Siaynoq also stands for fermentation because reality-or the belief that you know a reality, which is the same thing-always sets up a ferment in the universe."
"All of that in a single word, Lord?"
"And more! Siaynoq also contains the summoning to prayer and the name of the Recording Angel, Sihaya, who interrogates the newly dead."
"A great burden for one word, Lord."
"Words can carry any burden we wish. All that's required is agreement and a tradition upon which to build."