Addington, a S. county of the province of Ontario, Canada, bordering on the bay of Quinte, near the E. end of Lake Ontario; area about 2,000 sq. m.; pop. in 1871, 21,312. The county is about 122 m. long, and from 7 to 18 wide. It has between 20 and 30 lakes, the longest of which, Massanogo, is about 50 m.

long. The northern townships are new and thinly settled. The chief occupations are agriculture and lumbering. Chief town, Bath.