Which word describes a person who spends money extravagantly?

The word that describes a person who spends money extravagantly is "spendthrift." This term specifically refers to someone who is overly indulgent in their spending habits, often wasting money on unnecessary items or experiences. Spendthrifts tend to prioritize immediate gratification over financial prudence, leading to a carefree attitude towards their finances.

In contrast, the other words suggest a more measured or careful approach to spending. "Thrifty" denotes a person who is careful in using their resources, often finding ways to save money. "Economical" implies a focus on efficiency and cost-effectiveness in spending. "Saver" refers to someone who actively sets aside money rather than spending it freely. The distinct nature of a spendthrift lies in their excessive spending behavior, making it the only term fitting the description provided in the question.