Rubicon

noun

Ru·​bi·​con ˈrü-bi-ˌkän 

: a bounding or limiting line

especially : one that when crossed commits a person irrevocably

Did you know?

In 49 B.C., Julius Caesar led his army to the banks of the Rubicon, a small river that marked the boundary between Italy and Gaul. Caesar knew Roman law forbade a general from leading his army out of the province to which he was assigned. By crossing the Rubicon, he would violate that law. "The die is cast," he said, wading in. That act of defiance sparked a three-year civil war that ultimately left Julius Caesar the undisputed ruler of the Roman world. It also inspired English speakers to adopt two popular sayings -crossing the Rubicon and the die is cast-centuries later. Rubicon has been used in English as the name of a significant figurative boundary since at least the early 1600s.

Examples of Rubicon in a Sentence

Recent Examples on the Web

While no organization likes to lose, the fortune-shifting nature of the NFL Draft creates a Rubicon for the teams that do. —J.j. Bailey, The Athletic, 5 Jan. 2025

Even before it was done training, OpenAI knew the model was crossing some sort of AI Rubicon. —Steven Levy, WIRED, 21 Nov. 2024

And like all empires, this gang will experience a rise, a heyday, a Rubicon crossing and a fall. —David Fear, Rolling Stone, 21 June 2024

Word History

Etymology

Latin Rubicon-, Rubico, river of northern Italy forming part of the boundary between Cisalpine Gaul and Italy whose crossing by Julius Caesar in 49 b.c. was regarded by the Senate as an act of war

First Known Use

1613, in the meaning defined above

Phrases Containing Rubicon

• crossed the Rubicon
• the Rubicon

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Geographical Definition

Rubicon

geographical name

Ru·​bi·​con ˈrü-bi-ˌkän 

river 15 miles (24 kilometers) long in north central Italy flowing east into the Adriatic Sea