Illyricum (il-lĭr'i-kŭm). A Roman province of southeastern Europe, lying along the eastern coast of the Adriatic, from the boundary of Italy on the north to Epirus on the south, and contiguous to Mœsia and Macedonia on the east. On account of the insurrection of the Dalmatians, b.c. 11. the province was divided, and the northern portion called Dalmatia: the southern portion remained one of the Senate's provinces. Paul preached round about unto Illyricum. Romans 15:19.