What term describes someone who is excessively sparing or frugal?

The term that describes someone who is excessively sparing or frugal is "parsimonious." This word is often used to refer to individuals who are unwilling to spend money or use resources freely, even to the extent that it may be detrimental to themselves or others. In a broader sense, being parsimonious implies a level of extreme thriftiness that goes beyond simple frugality.

In contrast, the other terms provided paint a very different picture. "Generous" describes someone who is willing to give or share more freely and is the opposite of being parsimonious. "Lavish" denotes a sense of abundance and extravagant spending, which stands in stark contrast to frugality. Lastly, "sumptuous" refers to something rich, luxurious, and splendid, further reinforcing the idea of excess rather than sparingness. Thus, in the context of describing someone who is excessively sparing or frugal, "parsimonious" is the most appropriate term.