亏损 (kuī sǔn) is a noun meaning 'loss'—most commonly a financial loss, such as when a business earns less money than it spends. The character 亏 (kuī) means 'to lack' or 'to be deficient', while 损 (sǔn) means 'to damage' or 'to impair'; together, they convey the idea of a harmful shortfall or reduction in value. This term is frequently used in business, accounting, and economics contexts, but can also describe non-monetary losses, such as health or energy loss in traditional Chinese medicine.

It’s often paired with verbs like 出现 (to occur), 避免 (to avoid), or 扩大 (to widen), and commonly appears in phrases like 严重亏损 (serious loss) or 年度亏损 (annual loss). While it sounds formal, it’s standard in news reports, company statements, and everyday discussions about finances or wellbeing. Unlike the more colloquial 亏钱 (kuī qián), 亏损 carries a neutral-to-formal register and is preferred in written or professional speech.