灰心 (huī xīn) literally combines 灰 (huī, 'ash' or 'gray') and 心 (xīn, 'heart'), evoking the image of a heart turned to cold, lifeless ash — symbolizing loss of enthusiasm, hope, or motivation. It describes the emotional state of becoming discouraged, disheartened, or losing confidence after repeated setbacks or disappointment.

This word is commonly used in personal, academic, or professional contexts when someone gives up on a goal due to frustration or perceived failure. While it functions primarily as a verb (e.g., 他灰心了), it can also act as an adjective before nouns (e.g., 灰心的情绪). It carries a slightly literary or formal tone compared to colloquial alternatives like 没劲儿 or 打退堂鼓, and is often paired with verbs like 感到, 变得, or 使…灰心 to express cause or result.