肝要|かんようkan'you[0]heiban (flat)

1. na-adjective, nounextremely important; essential; vital; crucial
   危機ききの際さいにも冷静れいせいさを失うしなわず、狂気きょうきに走はしるのを避さけることが肝要かんようである。↗

   It is essential to keep calm in a time of crisis and avoid going haywire.

• Synonym肝心かんじんNeutralEveryday word for what is crucial or critical, as in 「肝心なのは」. Same meaning as 「肝要」 but far more common in speech; 「肝要」 is the more written variant.
• Synonym重要じゅうようNeutralThe most common, all-purpose word for important; it modifies almost anything. 「肝要」 is more written and stresses being the key to success or failure.
• Synonym大事だいじNeutralCommon in everyday speech for important or precious things, and also for major incidents. 「肝要」 is more written and formal in tone.
• Synonym大切たいせつNeutralEveryday word for important or precious, and it can also carry the sense of treasuring or taking care. 「肝要」 has no such 'cherish' nuance.
• Synonym緊要きんようFormalFormal word meaning critical and pressing. It adds a sense of urgency that 「肝要」 lacks, though both stress great importance.
• Synonym重大じゅうだいNeutralMeans serious or grave, typically of incidents and responsibility, as in 「重大な事故」. 「肝要」 says something is crucial but implies no severity.
• Synonym枢要すうようFormalFormal word for something central and most critical, as in 「枢要な地位」. Used mostly of positions and organizations rather than general importance.
• Related不可欠ふかけつWrittenA written/formal word meaning indispensable: without it, something cannot work or exist. 「肝要」 instead stresses that something is the crucial point.
• Related必須ひっすNeutralRefers to what is required or must be had, as in 「必須条件」. It stresses being a necessary condition, while 「肝要」 stresses being the key point.
• Related必要ひつようNeutralThe most common word for necessary or needed. It only says something is required, while 「肝要」 stresses that it is the crucial point.
• Related主要しゅようNeutralMeans main or principal, as in 「主要都市」. It points to the central, main part of something; 「肝要」 points to the crucial point itself.
• Related切要せつようWrittenWritten/formal and now rarely used; it means vitally important. In everyday speech say 「肝心」 or 「非常に大切」 instead.
• Related緊切きんせつWrittenWritten/formal word for urgent or pressing matters; it can also mean fitting closely together. Its focus is urgency, not the crucial-point sense of 「肝要」.
• Antonym不要ふようNeutralAntonym: unnecessary or superfluous — the direct opposite of the extreme importance that 「肝要」 expresses.
• Antonym無用むようNeutralAntonym: useless or unneeded; also seen on signs like 「無用の者立入禁止」. It stands at the opposite pole from 「肝要」.

Use 「肝要」 in written or formal prose to stress that something is the crucial point, as in 「〜が肝要だ」. In speech prefer 「肝心」 or 「大事」, and for plain 'important' use 「重要」. 「必要」「必須」 are about necessity and 「不可欠」 (written) about being indispensable; 「大切」 adds preciousness, 「主要」 means main, 「枢要」「緊要」 are formal, 「切要」「緊切」 are rare written words, 「重大」 is about gravity; antonyms 「不要」「無用」.

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

1. 非常ひじょうに重要じゅうようまたは大切たいせつであること。