Serbia UK /ˈsɜː.bi.ə/US /ˈsɝ.bi.ə/ noun2 •A country on the Balkan Peninsula in Southeastern Europe. Official name: Republic of Serbia. Capital and largest city: Belgrade. Part of Yugoslavia until 1992, then part of Serbia and Montenegro until 2006.The 153-page ruling from the International Court of Justice means that modern-day Serbia will not have to pay restitution to Croatia, which in 1991 split from what was then Yugoslavia. — 2015 •A geographic region of Southeastern Europe.