(Sanskrit) “The Great Day.” A period of universal activity, as opposed to a Mahapralaya, a cosmic night or period of rest.

"Truthfully, the quantities of years assigned to a Cosmic Day are symbolic. The Cosmic Night arrives when the ingathering of the perfect souls is complete, which means, when the Cosmic Day is absolutely perfected." - Samael Aun Weor, The Pistis Sophia Unveiled

"I was absorbed within the Absolute at the end of that Lunar Mahamanvantara, which endured 311,040,000,000,000 years, or, in other words, an age of Brahma." - Samael Aun Weor, The Revolution of Beelzebub