Hackensack was the exonym given by the Dutch colonists to a band of the Lenape, a Native American tribe. The name is a Dutch derivation of the Lenape word for what is now the region of northeastern New Jersey along the Hudson and Hackensack rivers. While the Lenape people occupied much of the mid-Atlantic area, Europeans referred to small groups of native people by the names associated with the places where they lived.
A phratry of the Lenape, the Hackensack spoke the Unami dialect, one of the three major parts of the Lenape languages, which were part of the Algonquian language family. Unami meant the "people down river", and they identified themselves with the totem of the turtle ("Turtle Clan"). Their territory has been variously spelled Ack-kinkas-hacky, Achkinhenhcky, Achinigeu-hach, Ackingsah-sack (among others) and translated as "place of stony ground" or "mouth of a river". It included the areas around the Upper New York Bay, Newark Bay, Bergen Neck, the Meadowlands, and the Palisades. Other bands of Unami speakers in the area included: the Raritan on Staten Island/Raritan Bay, the Acquackanonk on the Passaic River, and the Tappan along the Palisades and Pascack Valley. These groups, along with the Wappinger in the Hudson Valley, and Canarsee and Rockaway on Long Island, were sometimes collectively called the River Indians.