困乏 is an adjective meaning 'exhausted' or 'fatigued', describing a physical or mental state of severe tiredness. The character 困 means 'trapped', 'hard-pressed', or 'in difficulty', evoking a sense of being weighed down; 乏 means 'lacking', 'insufficient', or 'worn out'. Together, they intensify the sense of depletion — not just sleepy, but deeply drained, often after prolonged effort, illness, or stress. It’s more formal and literary than common alternatives like 累 (lèi) and carries a slightly stronger, sometimes somber connotation.

This word appears frequently in written Chinese — novels, news reports, medical contexts — and in formal speech, especially when describing chronic fatigue, recovery from illness, or exhaustion due to hardship. It’s rarely used in casual conversation among friends; instead, it suits contexts where seriousness, empathy, or gravity is appropriate — for example, describing an elderly person’s frailty or a worker’s burnout after months without rest.