'Nilesh' means 'the Blue God',
and is one of the alternate names for
Vishnu, "The Preserver."
Later, the name was also used to refer to Shiva, "The Destroyer of Evil", "The King."
The name is a combination (sandhi) of two words:
Neel ("blue") and Ish ("Lord" or "God").
Ish or Esh is also a Sanskrit word for head. Hence, the name can also be interpreted as 'Blue Head,' which refers to Lord Shiva.
Nilesh also refers to a third deity: Krishna. Krishna is also referred to as the Blue God because of the darker
skin which is always displayed in pictures and statues in the
colour blue.