'Nilesh' means 'the Blue God', and is one of the alternative names for Vishnu, "The Preserver."
'Nilesh' also means "The Destroyer of Evil." So it is alternative name for lord shiva.The name comes to shiva because he had poison of bluish in appearnce,by that he became a bluish.
The name is a combination (sandhi) of two words: Neel (Blue) and Ish (Lord or God).
(Sent from: nilesh)