Naugatuck (nôg´ətŭk´), industrial borough (1990 pop. 30,625), New Haven co., SW Conn., on both sides of the Naugatuck River; settled 1704, inc. 1844. In 1843, Charles Goodyear established the Naugatuck India-Rubber Company there. Rubber is still an important industry in Naugatuck. Other manufactures include candy, chemicals, brass and copper products, and plastics.

Naugatuck, river, 65 mi (105 km) long, rising in NW Conn. and flowing S, past Waterbury, to the Housatonic River at Derby. It furnishes water power for the remaining industrial plants along its shores. Thomaston Dam (completed 1960), built for flood control, forms a reservoir on the river.