E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Konx Ompax.
The words of dismissal in the Eleusinian Mysteries. A correspondent in Notes and Queries says knox or kogx is the Sanscrit Canscha (the object of your desire); ompax is om (amen), pacsha (all is over). If this is correct, the words would mean, God bless you, Amen, The ceremonies are concluded. When a judge gave sentence by dropping his pebble into the urn of mercy or death, he said Pacsha (I have done it). The noise made by the stone in falling was called pacsha (fate), and so was the dripping noise of the clepsydra, which limited the pleaders quota of time.