忍耐 (rěn nài) is a compound noun meaning 'forbearance' or 'patience' — the ability to endure difficulty, delay, discomfort, or provocation without complaint, anger, or giving up. The first character 忍 (rěn) means 'to endure' or 'to suppress (an emotion or impulse)', while 耐 (nài) means 'to bear', 'to withstand', or 'to tolerate'. Together, they emphasize sustained inner composure in the face of hardship — not passive resignation, but active, conscious self-restraint.

This word appears frequently in contexts involving personal growth, interpersonal relationships, work challenges, and long-term goals. It’s often used in advice, motivational speech, or reflective writing (e.g., 'Success requires patience'). While it can describe a trait ('She has great forbearance'), it’s more commonly used in phrases like 有忍耐 (has patience), 缺乏忍耐 (lacks patience), or 忍耐力 (endurance/patience as capacity). It carries a slightly formal or literary tone, less common in casual spoken Chinese than simpler words like 耐心 (nàixīn).