district south of Macedonia and east of Epirus, from Greek Thessalia (Attic Thettalia), an Illyrian name of unknown origin. Related: Thessalian. The city of Thessalonika on the Thermaic Gulf was ancient Therme, renamed when rebuilt by the Macedonian king Cassander, son of Antipater, and named in honor of his wife, Thessalonica, half-sister of Alexander the Great, whose name contains the region name and Greek nike "victory." The adjectival form of it is Thessalonian Related: Thessalonians.