Middleborough (frequently written as Middleboro) is a town in Plymouth County, Massachusetts, United States. The population was 23,116 at the 2010 census.
The town was first settled by Europeans in 1661 as Nemasket, later changed to Middlebury, and officially incorporated as Middleborough in 1669. The name Nemasket came from a Native American settlement along the small river that now bears the same name. Nemasket may have meant "place of fish", due to the large amount of herring that migrate up the river each spring. There are no contemporary records that indicate the name Middlebury was taken from a place in England. The names Middlebury and Middleborough were actually derived from the city of Middelburg, Zeeland, the westernmost province of the Netherlands. Middelburg was an international intellectual center and economic powerhouse. The English religious dissenters known as the Brownists developed their governing institutions in Middelburg before emigrating on the Mayflower, and were the earliest settlers of Middleborough.
During King Philip's War (1675–76), the town's entire populace took shelter within the confines of a fort constructed along the Nemasket River. The site is located behind the old Memorial High School (now a kindergarten), and is marked by a state historical commission marker along Route 105.