a stream in N Italy: in ancient times the boundary between Italy and Cisalpine Gaul. By leading his army across it and marching on Rome in 49 bc, Julius Caesar broke the law that a general might not lead an army out of the province to which he was posted and so committed himself to civil war with the senatorial party
2. (sometimes not capital)
a point of no return
3.
a penalty in piquet by which the score of a player who fails to reach 100 points in six hands is added to his or her opponent's
4. cross the Rubicon
Rubicon in American English
(ˈrubɪˌkɑn)
small river in N Italy that formed the boundary between Cisalpine Gaul & the RomanRepublic: when Caesar crossed it (49 b.c.) at the head of his army to march on Rome, he began the civil war with Pompey