Main Entry: Ru·bi·con

Pronunciation: \ˈrü-bi-ˌkän\

Function: noun

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

Date: 1626

: a bounding or limiting line; especially : one that when crossed commits a person irrevocably