the Rubicon noun Trending Now: More Trending: charlatan lowlife kakistocracy slimeball salacious SEE ALL See What's Trending Now See More Trending Words What's Trending Now More Trending Words charlatan 'faker or fraud' lowlife 'a person of low moral character' kakistocracy 'government by the worst people' slimeball 'a morally repulsive or odious person' salacious 'arousing or appealing to sexual desire' SEE ALL Time Traveler! Explore the year a word first appeared Definition of the Rubicon : a limit or point that is reached when the results of one's actions cannot be changed Once you've crossed the Rubicon there's no going back. Word by Word Definitions Rubicon play : a bounding or limiting line See the full definition of Rubicon Seen and Heard What made you want to look up the Rubicon? Please tell us where you read or heard it (including the quote, if possible). show hide