‘严于律己’ literally means ‘strict in regulating oneself’ — it describes someone who holds themselves to high moral, ethical, or behavioral standards, often with self-discipline and personal accountability. The character 严 (yán) means ‘strict’ or ‘serious’; 于 (yú) is a preposition indicating ‘with respect to’ or ‘in regard to’; 律 (lǜ) means ‘to regulate’ or ‘to discipline’; and 己 (jǐ) means ‘oneself’. Together, the phrase emphasizes internal rigor rather than harshness toward others.

This expression is commonly used in formal, educational, or moral discourse — especially when praising integrity, leadership, or personal growth. It frequently appears in speeches, essays on character development, and discussions about professional ethics. While it carries positive connotations of responsibility and humility, it’s not used casually in everyday speech; rather, it reflects an aspirational or evaluative standard for conduct.