[ 'ru:bɪk(ə)n , -kɒn ]
■ noun
1》 a point of no return.
2》 (in piquet) an act of winning a game against an opponent whose total score is less than 100.
Origin
the name of a stream in NE Italy marking the ancient boundary between Italy and Cisalpine Gaul, which Julius Caesar crossed in 49 BC, breaking the law and so committing himself to war.