1. The boundary in ancient times between Italy and Gaul; Caesar's crossing it with his army in 49 BC was an act of war
    
2. A line that when crossed permits of no return and typically results in irrevocable commitment
   - point of no return

Derived forms: Rubicons

Type of: bound, boundary, bounds, contrast, demarcation, dividing line, line

Encyclopedia: Rubicon, WI