What term describes a person who lives very meagerly to save money?

The term that describes a person who lives very meagerly to save money is "miser." A miser is someone who is extremely frugal and reluctant to spend even minimal amounts of money, often to the point of living in uncomfortable conditions or foregoing basic luxuries. This behavior is primarily motivated by a desire to accumulate wealth rather than to enjoy spending it.

In contrast, the other terms do not align with this definition. A spendthrift is someone who spends money freely and carelessly, often leading to financial difficulties. A philanthropist is an individual who seeks to promote the welfare of others, generally through charitable donations and generous spending. Lastly, extravagant refers to a person who spends excessively or indulges in lavish lifestyles, which is the opposite of meager living to save money.