It means fatal, irreparable, very large, notorious, thickness, size, rude, outrageous. It almost always refers to a monumental and irreparable mistake. Crassus was a Roman politician, called Marcus Licinius Crassus, Triumvir and consul. An error military yours, which led him to death originated the Latin phrase "Errare Crassus", big mistake, Crassus, fatal error error.