Joensuu (yôˈĕnsō) [key], city (1998 pop. 51,113), Eastern Finland prov., SE Finland. It is the trade center of the forest region of NE Karelia, has plywood mills, and is an important lake port. It was chartered in 1848 as a copper town. The modern city hall was designed by Eliel Saarinen. A university was established there in 1969.