proskynesis

From the Greek προσκύνησις, coming from the verb προσκυνέω, which means “to bring the hand to the mouth to send a kiss”, it is an act of reverence that the Assyrians and later the Persians used when they were in the presence of a sovereign or other person of high rank. In the Byzantine world, it was a ceremonial obligation to prostrate oneself before the Basileus.