至誠|しせいshisei[0]heiban (flat)

1. nounsincerity; devotion

• Synonym誠意せいいNeutralEveryday word for sincerity or good faith, common in business, as in 「誠意を示す」. Plainer and far more frequent than the lofty, written 「至誠」.
• Synonym誠実せいじつNeutralDescribes an honest, dependable character; a common everyday adjectival noun. Much plainer than 「至誠」, which names sincerity at its extreme.
• Synonym誠心せいしんWrittenWritten word for a sincere heart, now mostly in the set phrase 「誠心誠意」; sincere but not as extreme as 「至誠」.
• Synonym真心まごころNeutralEveryday word for a true, unadorned heart, as in 「真心を込めて」; warmer and more colloquial than 「至誠」.
• Synonym丹精たんせいNeutralDevoted care and painstaking effort, as in raising plants 「丹精込めて」. The emphasis is on the work poured in, not the virtue itself.
• Synonym誠まことNeutral「誠」 itself: a true heart or truth, also usable as an adverb. At home in both speech and writing, and far more common than 「至誠」.
• Synonym信しんNeutralIntegrity, trustworthiness and credit, and by extension religious faith. A much wider range of meaning than 「至誠」.
• Synonym実意じついWrittenWritten and rare: a true heart or one's real intentions; in daily speech say 「真心」 instead.
• Synonym信実しんじつWrittenWritten and rare: honesty that keeps faith; centers on trustworthiness and is close in sense to 「至誠」.
• Synonym真情しんじょうWrittenWritten word for genuine, unfeigned feeling; points at the emotion itself, not at character as 「至誠」 does.
• Synonym真率しんそつWrittenWritten and rare: sincere and frank, hiding nothing; the stress is on candor rather than depth of sincerity.
• Synonym丹心たんしんWrittenWritten and rare: a devoted, loyal heart. Close to 「至誠」; found mainly in Sino-Japanese poetry and prose.
• Synonym篤実とくじつWrittenWritten: kind, sincere and warm-hearted; highlights gentle, humane treatment of others rather than sheer sincerity.
• Synonym至情しじょうWrittenWritten and rare: deeply genuine feeling, the natural emotions of the human heart. About feeling itself, not the steadfast sincerity of 「至誠」.
• Synonym赤心せきしんWrittenWritten and rare: utter devotion, a loyal open heart; survives mainly in historical documents.
• Synonym赤誠せきせいWrittenWritten and rare: red-hot sincerity without a trace of falsehood — in meaning the closest of all to 「至誠」.
• Synonym至心ししんWrittenWritten and rare: the utmost sincere heart, often in Buddhist contexts. Synonymous with 「至誠」 but little used today.
• Related忠誠ちゅうせいNeutralLoyalty to a lord, country or other master; the focus is the object of allegiance. 「至誠」 is about a sincere heart, not devotion to someone.
• Related実直じっちょくNeutralHonest, steady and dutiful; praises a hardworking, down-to-earth character. Lacks the lofty ring of 「至誠」.
• Related誠まことNeutral「誠」 itself: a true heart or truth, also usable as an adverb. At home in both speech and writing, and far more common than 「至誠」.
• Related真面目まじめNeutralThe everyday word for being serious and honest; stresses one's attitude to work and duties. Commonest of all, and much plainer than 「至誠」.
• Related真正直ましょうじきCasualColloquial: completely honest, with no falsehood anywhere. Plain and emphatic, without the solemn loftiness of 「至誠」.
• Related衷情ちゅうじょうWrittenWritten and rare: the true feelings deep in one's heart; mostly in letters pleading one's case.
• Related篤厚とっこうWrittenWritten and rare: warm-hearted and honest, generous in one's dealings with people.
• Antonym偽りいつわりNeutralA lie or fabrication — the very opposite of the sincerity of 「至誠」.
• Antonym不誠実ふせいじつNeutralDishonesty or bad faith; the direct antonym of the sincerity of 「至誠」.

For everyday sincerity use 「誠意」 (intentions, business) or 「真心」 (a true heart); for an honest character use 「誠実」. 「至誠」 itself is sincerity at its utmost, a written, lofty word best known from the maxim 「至誠天に通ず」. Among the rarer written synonyms, 「赤誠」 is closest in sense, 「誠心」 survives in 「誠心誠意」, and 「至心」 appears in Buddhist language. 「忠誠」 is loyalty to a master, 「真面目」 is everyday earnestness, and 「偽り」 and 「不誠実」 are its opposites.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 非常ひじょうに誠実せいじつなこと。また、その心こころ。