Wordorigins.org

The Commonwealth of Massachusetts is named after the Indian tribe. The name in the Massachusett language is from massa (great) + wadchu (hill). The name is a reference to what is now known as the Great Blue Hill in Milton, about ten miles south of Boston. At all of 635 feet (194 m), the hill isn’t that great in absolute terms, but it’s one of the largest in the area.

(Sources: Oxford English Dictionary, 3rd Edition; Illustrated Dictionary of Place Names; Webster’s Third New International Dictionary)