[roo-bi-kon] 
| 1. | a river in N Italy flowing E into the Adriatic. 15 mi. (24 km) long: in crossing this ancient boundary between Cisalpine Gaul and Italy, to march against Pompey in 49 b.c., Julius Caesar made a major military commitment. |
| 2. | cross or pass the Rubicon, to take a decisive, irrevocable step: Our entry into the war made us cross the Rubicon and abandon isolationism forever. |
| Ru·bi·con (rōō'bĭ-kŏn') n. A limit that when passed or exceeded permits of no return and typically results in irrevocable commitment. [Latin Rubicō, Rubicōn-, Rubicon, a short river of north-central Italy, the crossing of which by Julius Caesar and his army in 49 B.C. began a civil war.] |
A river in northern Italy that Julius Caesar crossed with his army, in violation of the orders of the leaders in Rome, who feared his power. A civil war followed, in which Caesar emerged as ruler of Rome. Caesar is supposed to have said, “The die is cast” (referring to a roll of dice), as he crossed the river.
Note: “Crossing the Rubicon” is a general expression for taking a dangerous, decisive, and irreversible step.
bɪˌkɒn