a river in N Italy flowing E into the Adriatic. 15 miles (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.
Idioms
cross/pass the Rubicon, to take a decisive, irrevocable step: Our entry into the war made us cross the Rubicon and abandon isolationism forever.
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
(sometimes not capital)a point of no return
a penalty in piquet by which the score of a player who fails to reach 100 points in six hands is added to his opponent's
cross the Rubiconorpass the Rubiconto commit oneself irrevocably to some course of action
in phrase to cross (or pass) the Rubicon "take a decisive step," 1620s, a reference to a small stream to the Adriatic on the coast of northern Italy which in ancient times formed part of the southern boundary of Cisalpine Gaul; crossed by Caesar Jan. 10, 49 B.C.E., when he left his province to attack Pompey. The name is from Latin rubicundus "ruddy," in reference to the color of the soil on its banks.
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.
