誠まことに

ま

こ

と

に

Common wordJLPTN1Freq.FrequencyTop 10,000

Meanings

Adverb expressing strong emphasis or sincerity. Used in both formal and casual contexts. Can intensify adjectives or express heartfelt feelings.

誠まことに〈形けい容よう詞し〉truly ~ (used to intensify polite apologies, thanks, or formal remarks)
誠まことに申もうし訳わけございません。
I am truly sorry.
誠まことに残ざん念ねんながら〈事こと〉very regrettably, ~ (formal way to soften bad news)
誠まことに残ざん念ねんながら、今こん回かいは不ふ採さい用ようとなりました。
We regret to inform you that you were not selected this time.

本ほん当とうにN5
本当に is the everyday word for 'really/truly', while 誠に is more formal and often used in written or polite speech.
実じつにN3
実に also means 'really/indeed' but sounds less formal and more literary than 誠に, which leans toward polite or ceremonial use.
心こころからN3
誠に is a more formal, often written or business-register word for sincerity, while 心から feels warmer and more personal.
さだ
真に is a modern formal/literary word meaning 'truly', whereas 定 (さだ) carries the same sense but is confined to archaic or classical usage.
真しんにN1
誠に is a very formal, polite adverb often used in apologies and greetings (誠に申し訳ございません), while 真に focuses on genuine, essential truth rather than politeness.

誠まことに
Standard kanji spelling; high priority.
真まことに
Alternate kanji form, less common than 誠に.
寔まことに
rarely-used kanji form
Rarely used kanji form.
実まことに
rarely-used kanji form
Rarely used kanji form; can be confused with 実に (じつに).
洵まことに
rarely-used kanji form
Rarely used kanji form.

Derived from the noun 誠 (まこと, 'truth, sincerity') with the adverbial particle に. The kanji 誠 reflects the core meaning of sincerity.