Gitche Manitou (Gitchi Manitou, Kitchi Manitou, etc.) means "Great Spirit" in several Algonquian languages. The term was also utilized to signify God by Christian missionaries, when translating scriptures and prayers, etc. into the Algonquian languages.
Manitou is a common Algonquian term for spirit, mystery, or deity.
Read more about Gitche Manitou: Anishinaabe, Other Tribes, Related Spirits, Manitou As Mystical Term