"Prodigal" literally means wastefully or recklessly extravagant.
The Original Reference: "The Prodigal Son"
The term comes from the Parable of the Prodigal Son in the Bible (Luke 15:11-32). In the story:
A young son asks for his inheritance early, leaves home, and squanders all his money on reckless and extravagant living. Eventually, he becomes destitute and returns home, expecting punishment. Instead, his father joyfully welcomes him back with open arms and celebrates his return.