Sanskrit for “Chief Lord.” A title or rank. “The head of a spiritual Hierarchy.” - from the Theosophical Glossary. Can also be a reference to the Holy Spirit.
"The seventh initiation confers upon us the degree of “Maha-choan. The Maha-choan becomes a guardian of the Akashic archives and director of the works of the great White Lodge." - Samael Aun Weor, The Zodiacal Course