せいしんせいい 誠心誠意 LinksSentence search for 誠心誠意Sentence search for せいしんせいいKanji details for 誠, 心 and 意Edit in JMdict Adverb (fukushi), Noun, Noun which may take the genitive case particle 'no'1. in all sincerity; with one's whole heart; whole-hearted devotionYojijukugo (four character compound) Discussions Log in to talk about this word.