The Indian surname Singh is is a Hindu Kshatriya name but now adopted by many different communities, from Sanskrit simha ‘lion’, hence ‘hero’ or ‘eminent person’. It is freely added to Rajput and Sikh male personal names and in the U.S. often serves as a Sikh surname. Singh was a name used by Rajput kings and in Rajasthan, the existing Raja's there have the title Singh. One of the tradition in rajput family was that the eldest son used to recieve diksha from guru and become sikh the surdar(head of the family). Now this last name is strongly associated with sikh even though this is the common middle name for rajputs.