Source : Webster's Revised Unabridged Dictionary (1913)

Sikhs \Sikhs\, n. pl.; sing. {Sikh}. [Hind. Sikh, properly, a
   disciple.]
   A religious sect noted for warlike traits, founded in the
   Punjab at the end of the 15th century.

Source : WordNet®

Sikh
     adj : of or relating to the Sikhs or their religious beliefs and
           customs

Sikh
     n : an adherent of Sikhism