Rubicon

n.

1.

(Anc. geog.) A small river which separated Italy from Cisalpine Gaul, the province alloted to Julius Cæsar.

Noun	1.	Rubicon - 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.	Rubicon - a line that when crossed permits of no return and typically results in irrevocable commitment Synonyms: point of no return

bound, boundary, bounds