There are a number of different synonyms for the word "un-thrifts" that can be useful depending on the context in which you are using the term. For example, if you are describing someone who is prone to spending too much money and being careless with their finances, you might use words like "spendthrift," "profligate," or "squanderer." On the other hand, if you are talking about someone who is simply not inclined to spend money at all, you might use terms like "tightwad," "miser," or "scrooge." Other synonyms for un-thrifts might include words like "frugal," "economical," or "thrifty," all of which suggest a more careful approach to managing one's finances.