Originally: a convert to Sikhism from Islam. In later use (from the end of the 19th cent.): (in the Punjab) a Sikh convert from the Chuhra group of outcastes (traditionally sweepers and scavengers).
Mid 19th century. From Urdu maḏhabī from Persian maḏhabī way of thinking, persuasion from Arabic maḏhabī denominational, sectarian from maḏhab denomination, school of thought + -ī.