冲动 (chōng dòng) describes a sudden, strong urge to act without thinking — it's often a temporary emotional impulse. Compared to 鲁莽 (lǔ mǎng 'reckless'), which suggests a habitual lack of caution, 冲动 is more about a momentary loss of control. 急躁 (jí zào 'impetuous') emphasizes impatience and irritability, while 冲动 focuses on the urge itself.