誠せい心しんせいしんFreq.FrequencyTop 50,000Meanings1nounsincerity; true heartA formal, somewhat literary noun for wholehearted sincerity or genuine devotion. Often used in set phrases like 誠心誠意.彼かれは誠せい心しん誠せい意い、問もん題だいの解かい決けつに取とり組くんだ。He tackled the problem with utmost sincerity.誠せい心しんをもってお詫わび申もうし上あげます。I offer my sincere apologies.