ろうせい 老成 LinksSentence search for 老成Sentence search for ろうせいKanji details for 老 and 成Edit in JMdict Na-adjective (keiyodoshi), Noun, Suru verb, Intransitive verb1. mature; experiencedNa-adjective (keiyodoshi), Noun, Suru verb, Intransitive verb2. precocious; mature for one's age Discussions Log in to talk about this word.