誠実|せいじつseijitsu[0]heiban (flat)

1. na-adjective, nounsincere; honest; faithful
   ナンシーには誠実せいじつさが欠かけているようだ。↗

   Nancy seems to lack sincerity.

• Synonym実直じっちょくWrittenWritten/formal prose. Honest, steady and dutiful in one's work; 「誠実」 stresses sincerity toward people and never deceiving them.
• Synonym律儀りちぎNeutralStresses keeping promises and honoring one's obligations to others, as in 「律儀な人」; 「誠実」 is about a true, undeceiving heart.
• Synonym信義しんぎWrittenWritten/formal prose. A noun for keeping faith and honoring obligations, as in 「信義に厚い」.
• Synonym真心まごころNeutralA noun for true, heartfelt sincerity, as in 「真心を込める」; carries a warm, affectionate nuance.
• Synonym誠意せいいNeutralA noun for good faith, as in 「誠意を見せる」; typical of apologies and negotiations.
• Synonym良心的りょうしんてきNeutralActing in good conscience; also used for fair prices or honest shops, as in 「良心的な店」.
• Synonym信しんWrittenWritten/formal prose. A noun for trustworthiness and faith; mostly seen in compounds.
• Synonym堅気かたぎNeutralA noun for a respectable, honest person or decent occupation, as opposed to the underworld.
• Synonym至誠しせいWrittenWritten/formal prose. A noun for utter, wholehearted sincerity.
• Synonym誠心せいしんWrittenWritten/formal prose. A noun for sincere intent, as in 「誠心誠意」.
• SynonymまめNeutralAbout being faithful to one's duty or to an original work, staying true without distortion, rather than about sincerity toward people.
• Synonym篤実とくじつWrittenWritten/formal prose. Sincere and kind-hearted; used mainly when appraising someone's character.
• Synonym信実しんじつWrittenWritten/formal prose. A noun for honesty and truthfulness; rare in modern usage.
• Related正直しょうじきNeutralEveryday word for being honest and not lying; also works as an adverb meaning 'frankly' or 'to be honest'.
• Related真面目まじめNeutralCommon everyday word focusing on a serious, earnest attitude rather than sincerity toward others.
• Related率直そっちょくNeutralAbout speaking frankly and directly, as in 「率直な意見」; it describes candor in words, not overall sincerity.
• Related誠まことWrittenWritten/formal prose. A noun for sincerity and a true heart, as in 「誠を尽くす」.
• Related清廉せいれんWrittenWritten/formal prose. A noun for integrity and freedom from greed, as in 「清廉潔白」; stresses not being corrupt.
• Related忠実ちゅうじつNeutralAbout being faithful to one's duty or to an original work, staying true without distortion, rather than about sincerity toward people.
• Related忠誠ちゅうせいWrittenWritten/formal prose. A noun for loyalty to a lord or organization, as in 「忠誠を誓う」.
• Related忠義ちゅうぎWrittenWritten/formal prose. A noun for loyalty and devotion, with a samurai-code flavor.
• Related廉潔れんけつWrittenWritten/formal prose. A noun for clean-handed, incorruptible uprightness.
• Related真正直ましょうじきNeutralAn emphatic form: honest through and through, to the point of being overly earnest.
• Related物堅いものがたいWrittenWritten/formal prose with an old-fashioned flavor: describes a person as proper, upright and dependable.
• Antonym嘘つきうそつきNeutralA noun for a liar, someone who tells untruths — the opposite of sincere 「誠実」.
• Antonym不誠実ふせいじつWrittenWritten/formal prose. The direct antonym of 「誠実」: insincere, dishonest, in bad faith.

Use 「誠実」 for treating people and things sincerely and without deception, as in 「誠実な人柄」 or 「誠実に対応する」. For simply not lying pick 「正直」, for a serious attitude 「真面目」, for keeping promises and obligations 「律儀」, for showing good faith 「誠意」, and for frank speech 「率直」. 「不誠実」 is the word for dishonesty.

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

1. 言葉ことばや行動こうどうに嘘うそがなく、心こころがこもっていること。