甚だしい|はなはだしいhanahadashii[5]nakadaka (mid-high)

1. i-adjectiveextreme; excessive; terrible; intense; severe; serious; tremendous; heavy (damage)
   あんなことを彼女かのじょに言ゆうなんて非常識ひじょうしきも甚はなはだしい。↗

   It's quite absurd of you to tell her that sort of thing.

• Synonym激しいはげしいNeutralFierce and violent in force or momentum, as in 「激しい雨」; 甚だしい instead stresses that a degree is outrageously large, usually with a negative nuance.
• SynonymひどいCasualColloquial and the everyday default: severe, terrible or cruel, as in 「ひどい渋滞」. In casual speech it stands in for 甚だしい.
• Synonym凄まじいすさまじいNeutralAstonishing and frightening, with a degree at the extreme, as in 「凄まじい音」.
• Synonym猛烈もうれつNeutralA na-adjective for fierce intensity, as in 「猛烈な暑さ」; it also serves as an adverb meaning 'extremely'.
• Synonym過度かどNeutralExcessive, as in 「過度の飲酒」; it stresses going beyond an appropriate limit.
• Synonym極端きょくたんNeutralExtreme, as in 「極端な例」; it stresses leaning heavily toward one side.
• Synonym極度きょくどNeutralUtmost, at the maximum degree, as in 「極度の緊張」; it stresses reaching the very limit.
• Synonym過剰かじょうNeutralBeyond the proper range, of quantity or degree, as in 「過剰な期待」「供給過剰」; 甚だしい focuses on an outrageous degree.
• Synonym過当かとうWrittenWritten/formal prose for excessive, as in 「過当競争」; used mostly in economic contexts.
• Related過激かげきNeutralRadical or extreme, as in 「過激な発言」; used mostly of speech, opinions and ideas.
• Related過多かたNeutralToo much or too many, as in 「情報過多」; it often appears as the second element of a compound.
• Related強烈きょうれつNeutralStrong and intense, as in 「強烈な印象」; it stresses powerful impact.
• Related激甚げきじんWrittenWritten/formal prose for extremely severe, as in 「激甚災害」; used mostly in official writing on disasters.
• RelatedものすごいCasualColloquial for tremendous or extreme, as in 「ものすごい人」; it works for both praise and criticism.
• Antonym軽微けいびWrittenWritten/formal prose for slight or minor; the opposite of 甚だしい.

Use 「甚だしい」 when a degree is outrageously large, usually with a negative nuance, as in 「誤解も甚だしい」; it leans toward written style. In speech, say 「ひどい」 or 「ものすごい」. For sheer force or momentum pick 「激しい」, and for exceeding a proper limit 「過度」. The opposite is 「軽微」.

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

1. 程度ていどがかけはなれて大おおきい様子ようす。