Diamond Jim Brady was a nickname given to a wealthy businessman of the late 19th and early 20th century. His moniker derived from his love of diamonds and his extravagant lifestyle. Other synonyms that can be used to describe someone like Diamond Jim Brady include a spendthrift, high roller, or a mogul. A spendthrift is someone who is known for their excessive spending and extravagance, much like Diamond Jim. A high roller is someone who is accustomed to wagering large sums of money on games and events, like Jim's penchant for gambling. Finally, mogul is a term used to describe a successful and wealthy individual in business or entertainment, like Diamond Jim's impressive fortune.