Abbassus or Ambasum (Latin: Abbassus;[1]Ἄμβασον[2]), was an ancient town of Phrygia, on the frontiers of the Tolistoboii, in Galatia.[3] It is, perhaps, the same as the Alamassus reported by of Hierocles,[4] and the Amadasse whose bishops attended early church councils. The editors of the Barrington Atlas of the Greek and Roman World note that its probable location is near Synnada,[5] however its precise location is not known.