深刻|しんこくshinkoku[0]heiban (flat)

1. na-adjective, nounserious; severe; grave; acute
   事態じたいは非常ひじょうに深刻しんこくである。↗

   The situation is very serious.

• Synonym重大じゅうだいNeutralNeutral. Describes things of great weight or consequence, as in 「重大な事故」「重大発表」; unlike 「深刻」, it does not suggest a problem worsening and causing worry.
• SynonymシリアスNeutralNeutral loanword for serious and earnest, often the mood of a work or an expression; 「シリアスな問題」 is possible, but 「深刻」 stresses a situation worsening and causing worry.
• Synonym重篤じゅうとくWrittenWritten/formal medical term for a critical condition, as in 「重篤な副作用」; not used for social problems.
• Synonym由々しいゆゆしいWrittenWritten/formal prose for a grave situation that cannot be ignored, as in 「由々しき事態」.
• Related甚だしいはなはだしいWrittenWritten/formal prose for an extreme, excessive degree, mostly of negative things, as in 「誤解も甚だしい」.
• Related重いおもいNeutralEveryday word for heavy, also used of a serious illness or heavy responsibility; 「深刻」 stresses a dire situation or a grave look, as in 「深刻な表情」.
• Antonym軽微けいびWrittenWritten/formal antonym: damage or errors are slight, the opposite of 「深刻な被害」; common in news reports and official documents.
• Antonym浅薄せんぱくWrittenWritten/formal word for shallow knowledge or thinking; not a strict antonym, as Japanese 「深刻」 never describes insight as 'deep'.

Use 「深刻」 for a problem worsening and causing worry, or a grave look, as in 「深刻な問題」「深刻な表情」. Use 「重大」 for weighty matters with big impact, 「重篤」 for critical illness, and the loanword 「シリアス」 for serious, earnest moods; the formal opposite of 「深刻な被害」 is 「軽微」.

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

1. 事態じたいが進行しんこうして問題もんだいが重大じゅうだいになっていること。また、そのさま。
2. 事態じたいの重大じゅうだいさに心こころが囚とらわれ重々おもおもしく受け止うけとめていること。また、そのさま。