| a port in W Ontario, in S Canada, on Lake Superior: created in 1970 by the merger of twin cities (Fort William and Port Arthur) and two adjoining townships. 108,411. |
Thun·der Bay  (thŭn'dər)  A city of southwest Ontario, Canada, on Thunder Bay, an inlet on the northwest shore of Lake Superior. A major port and industrial center, it was created in 1970 by the amalgamation of the twin cities of Port Arthur and Fort William. Population: 109,000. |