The term linguistically means a man of old age, and is used in that sense in Qur'anic Arabic. Later it came to be a title meaning leader, elder or noble, especially in the Arabian Peninsula, where shaikh became a traditional title of a Bedouin tribal leader in recent centuries. For example, it was the term used to refer to the leaders of Kuwait's ruling al-Sabah dynasty until June 19, 1961, when Kuwait joined the Arab League, and the title Emir was adopted. The title is also used by Arab Christians for elder men of stature, showing that it is independent of religion.
It also was used by sufi orders as an honorific for an elder sufi who has been authorized by the order to teach, initiate dervishes and otherwise lead a sufi circle or dergah. In this sense, it is not restricted to sufi elders, but to any learned man in religion, such as Faqihs, Muftis, and Muhaddiths.
In the Persian Gulf, the title is used for men of stature, whether they are managers in high posts, wealthy business owners, or local rulers.
The title is often more informally used to address learned men as a courtesy. As a general rule of thumb, one may call someone older than 60 years of age a shaikh.