small river in N Italy that formed the boundary between Cisalpine Gaul & the Roman Republic: when Caesar crossed it (49 ) at the head of his army to march on Rome, he began the civil war with Pompey
See Rubicon in American Heritage Dictionary 4
(ro͞oˈbĭ-kŏnˌ)
noun
A limit that when passed or exceeded permits of no return and typically results in irrevocable commitment.