Within Sufism, the branch of Islamic spirituality organized around structured orders called tariqas, sheikh denotes a specific and demanding role distinct from its broader honorific use elsewhere: the sheikh of a tariqa is a spiritual master who has himself completed the order's path under his own sheikh and has been formally authorized, through an ijazah, to guide disciples (murids) and, in turn, to authorize successors of his own, extending an unbroken chain of transmission, the silsila, that many orders trace back many generations to their founder and, ultimately, to the Prophet Muhammad.
A Sufi sheikh's authority over his murids is understood as primarily spiritual rather than administrative, involving practices such as dhikr, the ritual remembrance of God, and close personal guidance of each disciple's inner development, and a sheikh's reputation and following can extend well beyond his own order's formal structure if he becomes known for particular insight or effectiveness as a teacher. This tightly defined Sufi usage sits alongside the much looser, everyday Arabic use of sheikh for any respected older man, scholar, or tribal leader, and the two senses, spiritual master within a defined lineage and general honorific, are distinguished mainly by context rather than by any different word.