self-improvement; self-cultivation
Refers to the act of diligently improving one's own skills, knowledge, or character through personal effort.
He is always striving for self-improvement.
I study every day for self-improvement in languages.
自己啓発 often implies a broader, sometimes commercial or motivational approach to personal development, while 自己研鑽 emphasizes diligent, self-directed study and practice.
修養 is a more traditional term for moral and mental cultivation, often with a philosophical or spiritual nuance, whereas 自己研鑽 is more neutral and modern.
Compound of 自己 (self) and 研鑽 (diligent study or polishing). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for abstract nouns.