燃眉之急 literally means 'a fire burning one’s eyebrows' — an evocative idiom that conveys extreme urgency, as if danger is so immediate that your eyebrows are already catching fire. The phrase combines 燃 (to ignite), 眉 (eyebrows), 之 (a classical possessive or linking particle), and 急 (urgency or crisis). Though vivid and dramatic, it is used in formal and semi-formal contexts — not casual speech — to describe a critical, time-sensitive problem demanding instant attention.

This idiom originates from classical Chinese literature and remains common in modern written Chinese, news reports, official documents, and serious discourse. It emphasizes severity and immediacy more than ordinary words like 紧急 (urgent) or 危机 (crisis), often implying that delay would cause serious harm. While the imagery involves fire and body parts, it is not related to animals or physical burns — it’s purely figurative, rooted in expressive classical rhetoric.