define rubicon river
Freebase(0.00 / 0 votes)Rate this definition: Rubicon. The Rubicon is a shallow river in northeastern Italy, about 80 kilometres long, running from the Apennine Mountains to the Adriatic Sea through the southern Emilia-Romagna region, between the towns of Rimini and Cesena. The Latin word rubico comes from the adjective rubeus, meaning red.