While Cooper tried to make the name sound authentic, its meaning is unclear and likely just a combination of sounds that he thought sounded Native American.
Some have suggested that "Chingachgook" might be a combination of "ching" meaning "strong" or "brave" and "gook" meaning "person" or "man" in some Native American languages. However, this is purely speculative and there's no definitive evidence to support it.
Ultimately, the name "Chingachgook" is a fictional creation, and its meaning is left to interpretation.