誠心誠意(せいしんせいい)

せいしんせいい
noun, expression
in all sincerity; wholeheartedly
formalbusiness
1. in all sincerity, with one's whole heart
Acting with complete sincerity and dedication; putting one's whole heart into something.
誠心誠意(せいしんせいい)お詫(わ)び申(もう)し上(あ)げます。
I sincerely apologize from the bottom of my heart.
誠心誠意(せいしんせいい)尽(つ)くしますので、よろしくお願(ねが)いします。
I will do my utmost with complete sincerity, so please count on me.
彼(かれ)は誠心誠意(せいしんせいい)対応(たいおう)してくれた。
He dealt with the matter with complete sincerity.

Etymology

誠心(せいしん) (sincere heart) + 誠意(せいい) (sincerity)

  • 誠(せい): sincerity, truth
  • 心(しん): heart, mind
  • 意(い): intention, meaning

"With sincere heart and sincere intention" - doubling the concept of sincerity for emphasis.

Common patterns

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Formal. Often used in business contexts, apologies, or when emphasizing genuine commitment. Very common in customer service language.

general
Added 2026.1.17 15:48 · Revised 2026.10.4 4:16
06000/06248_seishinseii