"Nipmuck" is a derivative of the compound Algonquian word made up of NIPPE (fresh water, as an inland lake or pond) and AMAUG (literally, "fish taken by the hook"). Prior to colonial times all of the inland tribes were spoken of as "fresh water" people in contrast to the coastal nations. 

The reference to "fish taken from an inland lake" (Nippeamaug) probably relates to the plentiful supply of fish in the sacred waters of Chargoggagoggmanchaugagoggchaubunnagungamaug at the heart of Nipmuck territory.