The word "prodigalize" means to spend recklessly or wastefully. Its antonyms, on the other hand, are words that signify restraint or saving. For example, the word "frugal" means careful with money and not wasting anything. "Economical," which means avoiding waste or extravagance, is another antonym for prodigalize. Additionally, "conservative," which refers to a cautious approach and avoiding risks, can also be seen as an antonym for prodigalize. In short, the opposite of prodigalize is to be responsible with resources, avoid waste, and practice restraint in spending.