怠倦 (dài juàn) is a classical and literary noun meaning 'weariness that leads to negligence or slackness.' The character 怠 means 'negligent,' 'slack,' or 'lax,' often implying a moral or duty-related failure due to fatigue; 倦 means 'weary,' 'tired,' or 'jaded,' conveying physical or mental exhaustion. Together, they form a compound emphasizing not just tiredness, but the resulting decline in diligence, vigilance, or responsibility — a state where fatigue erodes conscientiousness.

This term appears most frequently in formal writing, historical texts, philosophical discourse, or critiques of behavior (e.g., official dereliction, spiritual complacency). It carries a subtle moral weight: it’s not neutral fatigue, but fatigue that compromises integrity or duty. While rarely used in casual speech, it remains recognizable to educated native speakers and appears in idioms like 怠倦成疾 ('negligence and weariness lead to illness') or in admonitions about self-discipline.