In Arabic, sheik is an honorific title, as in a Saudi oil sheik who makes the business news. Sheik also refers to a specific head of a tribe or family, or a leader in a Muslim community.
In parts of the Middle East, South Asia, and some Muslim areas of Africa, a sheik is a religious leader or cleric. Sometimes it's the way an Islamic scholar is addressed. In Arabic the word is shaykh, "chief" or "wise old man." Women in a royal family, or female scholars of Islam, have traditionally been called shaykhah. Sheik is also spelled sheikh and shaikh.