"head of an Arab family," also "head of a Muslim religious order," 1577, from Arabic shaykh "chief," lit. "old man," from base of shakha "to grow old." Popularized by "The Sheik," novel in Arabian setting by E.M. Hull (1919), and movie version "The Sheikh," 1921, starring Rudolph Valentino, which gave it a 1920s sense of "strong, romantic lover."
[sheyk, shahyk] 
