Thriftlessly is an adverb that conveys a sense of wastefulness or extravagance. There are several synonyms for this word, including recklessly, carelessly, improvidently, prodigally, and extravagantly. Each of these words implies a lack of concern for financial stability or responsibility. Recklessly suggests impulsiveness and a disregard for consequences. Carelessly implies a lack of attention to detail or a nonchalant attitude towards expenses. Improvidently suggests a lack of foresight or planning. Prodigally implies spending money lavishly and impulsively, usually beyond one's means. Finally, extravagantly implies excessive or unnecessary spending. All of these synonyms convey a sense of financial irresponsibility or disregard for budgeting, highlighting the importance of careful spending and savings.