尽心 (jìn xīn) literally means 'exhaust the heart' — where 尽 (jìn) conveys 'to use up completely' or 'to the utmost', and 心 (xīn) means 'heart' or 'mind'. Together, it expresses doing something with full sincerity, deep commitment, and undivided effort — not just physically, but emotionally and morally. It emphasizes inner dedication rather than outward results.

This phrase is commonly used in formal, respectful, or earnest contexts: describing how a teacher teaches, a doctor treats patients, or a child cares for aging parents. It often appears in written Chinese, speeches, or moral exhortations, and carries a warm, virtuous tone. While grammatically an adverb, it frequently modifies verbs like 做 (do), 照顾 (take care of), or 努力 (strive), and may appear as a predicate or complement after 是 or 很.