堪忧 is an adjective meaning 'cause for concern' or 'worrying', often used to describe situations that provoke serious anxiety or alarm. The character 堪 means 'to bear' or 'to withstand', and 忧 means 'worry' or 'anxiety'; together, they literally convey the sense of something so troubling that it is nearly unbearable — hence, deeply worrying. It is formal in register and commonly appears in written Chinese, especially in news reports, official statements, and academic or policy discussions.

This term is rarely used in casual speech and almost never as a standalone predicate; instead, it typically follows a subject noun or noun phrase (e.g., 形势堪忧, 状况堪忧) and functions as a predicative complement after 是 or implicitly in descriptive clauses. It conveys gravity and urgency, often implying that immediate attention or action is needed to address the troubling condition.