Billerica, town, Middlesex County, northeastern Massachusetts, on the Concord River; settled 1637, incorporated 1655. Manufactures include medical instruments, chemicals, furnaces, computer hardware, and electronic equipment. Originally known as Shawsheen, the community in 1655 adopted the name Billirikeyca (later shortened to Billerica), after Billericay, England. Population 6,840 (1990).
