Rebbe
Rebbe (Hebrew:רבי) /ˈrɛbɛ/ or /ˈrɛbi/, is a Yiddish word derived from the Hebrew word rabbi, which means "master, teacher, or mentor". Like the title "rabbi" it refers to teachers of Torah or leaders of Jewry.
In common parlance of modern times, the term "The Rebbe" is often used specifically by Hasidim to refer to the leader of their Hasidic movement.