Definitions for "Alter Rebbe"
(lit., "the Old Rebbe"): Rabbi Shneur Zalman of Liadi (1745-1812), the founder of the *Chabad-*Lubavitch trend within the chassidic movement; author of the Tanya, a classic text of the chassidic tradition, and Shulchan Aruch HaRav, a classic legal code
Rabbi Schneur Zalman of Liadi, founder of Chabad (1745-1812). Author of Tanya and Rav Shulchan Aruch, among numerous other works. His Shulchan Aruch is accepted as authoritative among all Chassidim.